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Why Isn't the Sky Blue?

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Sky with sun and clouds (Balaji.B/flickr/CC-BY-2.0)

What is the color of honey, and "faces pale with fear"? If you're Homer--one of the most influential poets in human history--that color is green. And the sea is "wine-dark," just like oxen...though sheep are violet. Which all sounds...well, really off. Producer Tim Howard introduces us to linguist Guy Deutscher, and the story of William Gladstone (a British Prime Minister back in the 1800s, and a huge Homer-ophile). Gladstone conducted an exhaustive study of every color reference in The Odyssey and The Iliad. And he found something startling: No blue! Tim pays a visit to the New York Public Library, where a book of German philosophy from the late 19th Century helps reveal a pattern: across all cultures, words for colors appear in stages. And blue always comes last. Jules Davidoff, professor of neuropsychology at the University of London, helps us make sense of the way different people see different colors in the same place. Then Guy Deutscher tells us how he experimented on his daughter Alma when she was just starting to learn the colors of the world around, and above, her.

Read more:

Guy Deutscher, Through the Language Glass: Why the World Looks Different in Other Languages

Homer, The Odyssey: The Fitzgerald Translation


Jules Davidoff and Guy Deutscher

Produced by:

Tim Howard

Comments [127]

Eileen from NY

As painter, the sky when bright has many shades of blues. From Ultramarine ( reddish to some, to cobalt, to gran, etc. Most artists paint a landscape sky in at least 3 shades of blue. And as far as the not using colors to describe before they were used as dyes ? May dyes were used for various shades of blue, violet, yellow, etc. long before Homer!

Mar. 15 2018 02:28 PM
D.N. O'Donovan from here

This is like the problem faced by the eskimo ethnologist when he showed an Englishman 27 colours of ice and snow. The Englishman just looked, and looked and looked and couldn't find any difference between them.

Cobalt was being found, and refined and made into blue glass ingots by 1500 BC. We know because we found them on the Uluburun wreck.

Mar. 13 2018 01:39 PM
N Webb

This hypothesis was actually addressed critically back in the late 19th century. The Rig Veda uses the Sanskrit word for blue, but the "no blue" philologists decided to count that word as black. When looking at the frequency of the color words in the Nibelungenlied (13th century) and Milton's Paradise Lost (17th century), the frequency generally matched the color descriptors in literature from antiquity. Reds and yellows were still the most common. (

Humans have been able to see blue just fine since there have been humans. Well, not all humans. Some humans are colorblind (which has physical causes, not linguistic) and some humans are totally blind. Like Homer famously was.

Jan. 19 2018 08:19 PM
brandon ingle from Cedar falls, IA

Their are so many different levels of color blind from people who just see different shades of color to people who can only process color in black and white. If this entire civilization was color blind it would be interesting to see what the percentage of color blind people are still present in that area compared to the rest of the world. Also if all of these people were color blind as they say it would be interesting to find text to see how they describe certain features that are undeniably blue such as the sky and ocean to answer one of the most difficult questions in the world; Is your blue the same as my blue?

Jan. 12 2018 01:19 AM
DP from St. Peters, MO

Don't you think we should have started by proving the constant? Have we established the sky has always been blue? What would it take for sky to be more of a red color... even if it were just for a century or so over a particular area? S, Homer might not have even been a person? I also think asking a toddler that has never discussed the sky what color it is must be like bringing in a stack of blue paper and asking someone, "What color is the picture on this one?" what's he talking about... there's no picture? Flip to the next, "What color is the picture on this one?" Still no picture, what's he talking about? Flip to the next one with a picture of a white fluffy cloud on it, but don't ask. Flip to the next one with a picture of a cloud don't ask. Flip to the next blank blue sheet of paper and ask what color is the picture on this one? Er... I dunno dad. White? It's not like she had never seen a cloud in the sky. The desire to give her dad the answer is strong with kids and it was impossible to stop the idea of a cloud from coming in. Maybe you do train your eyes though, like how a musician has trained his ear and can break down the different parts instead of hearing it as a whole. It was an interesting episode for sure. I just felt like you kinda threw it out there and it was only partially investigated. Thanks for the great shows though.

Mar. 20 2017 12:55 PM

I read a much deeper explanation of human color differentiation here:
Humans have a huge range of color perception, but our ability to categorize/label colors is very influenced by our culture and language. The article above even discusses that the location of color perception moves locations in our brains during our lifetime. In infancy, we perceive color using the right hemisphere of our brains, but in adulthood, our color perception utilizes the left hemisphere (the language hemisphere).

Don't you remember the internet sensation of the blue and black dress that many people perceived to be white and gold?

We also know that our brains have to decide if a color is a warm hue or a cool hue. The dress debate is about this dichotomy. Some people perceived the color to be warm, and so they "saw" a white and gold dress. Others perceived the color to be cool, and they saw a black and blue dress.

Jan. 25 2017 05:30 AM
Jen from Baltimore, MD

I find it odd that anyone is arguing that ancient Greeks weren't exposed to the color blue. It is the color of the Mediterranean Sea that they were sailing over through both the Iliad and Odyssey. The flag of Greece reflects their connection to the ocean.

Jan. 25 2017 05:00 AM

I would like to request that you do an episode on Sounds. :) I am extremely interested and was rather baffled to hear that the child had such an unsure answer as to what color the sky is. I was just blown aback and I had to rethink my perception of colors. The thing that crossed my mind which really blew me away is the color may just really actually be subjective. I now have rediscovered an incredible appreciation for colors once again. And by the way, thank you :D

Nov. 18 2016 08:45 PM
Victor Tepes from Virginia-USA

I have been considering this further. What about blue fruits, blue feathers, and what about the blue woad that the Celts used as blue warpaint. Certainly there must have been an appreciation for this part of the electromagnetic spectrum.

Aug. 27 2016 09:02 AM
Victor Tepes from Virginia-USA

I wonder what the ancients then saw in lapis lazuli.

Aug. 27 2016 12:41 AM

I am having a difficult time working with this commenting thumbs up/down, red flag system, but, for the few red flags I had posted on, I have to agree that the children whom were confused on saying that the sky was "white" or "blue" were giving answers to the learned response of their parents, who kept on insisting that it either was blue to themselves, and then asked the tykes to parrot what they perceived or else to ask over and over until they received the desired result. Anyways, it was a memory from my childhood that made me think that black Moors were once said to be portrayed in Medieval art as Indigo-faced invaders; making a judgment call like that was a matter of perception back in European History and is adopted here for this podcast in my opinion.

Aug. 22 2016 01:46 AM
rhonda magnus from santa monica, ca

Homer was blind.

Aug. 22 2016 12:21 AM

Did you know that "bronze" is the category where many copper alloys fall into, with fresh color ranging from the silver of speculum or arsenic bronze to the brown of "normal" bronze, with also yellow and red? And that if you take into account rusted bronze, very common as ornamentation, it then becomes, depending on the base somposition, green, blue or black (or even purple)? (silver, black, blue and red are normal colors for the sky, with yellow being possible in volcanic zones such as Greece's islands)

If we take "wine-dark" as the color of a bruise, sheep and ox become just "black", while the sea can be either "black", like during a storm, "purple" as it is naturally in several parts of the Medierranean, or "red" as when during a red tide (a not-so-uncommon phenomenon there).

And the word for "green" means technically "plant", which, specially in a hot climate before the invention of modern irrigation systems, includes shades of green, brown, yellow and slightly brown or burnt white.

Apr. 26 2016 09:07 AM
Justice Smith

I never knew that gladstone was so deep into the color of the sky. Not knowing that he was a very religious man was interesting also.

Apr. 22 2016 04:20 PM
r alexander fleming from Ontario Canada

I saw a few comments that referenced 'wave length'.
Would the "GreenHouse Effect" be a variable in how we perceive the color blue?

Jan. 21 2016 12:47 AM
Ashley from Kansas City, MO

I just came across an IFL science article that said blue eyes did not appear un humans until 6,000 to 10,000 years ago. It could be another explanation for there not being a word for it.

Dec. 22 2015 10:54 AM

FYI, the Blue Moon song is a cover by Snowblink.

Sep. 30 2015 11:42 PM

I know it seems pedantic but this constant american mispronunciation of names bugs me. The prime minister in question was Gladstone , last syllable pronounced /stən/
it's weak, not /stəʊn/ "Gladstən". Please get it right.

Aug. 27 2015 04:09 PM
Fatma from Denmark

I listened to this episode last night and absolutely loved it. So this morning I was still thinking about it, when I remembered a pre-Islamic Arabian legend about a blue-eyed woman who could see into the future. The woman's name was Zarqa' al-Yamama. Zarqa' in Arabic is the word for blue (feminine adjective. The masculine adjective is azraq). I don't know much about the origins of this legend or what the oldest record we have of it is, but it did get me thinking about blue as an eye-colour. Surely there were more Greeks with blue eyes than there were Arabs, so how come they still didn't have a word for the colour, I wonder.

I especially found this theory interesting, because, being an avid victorian literature reader, I've always thought that we have lost some of our ability to see the colours of the human face. We seem to fare much worse than the Victorians at noticing when someone is blushing or when someone is pale and sick. Maybe it's all the make-up that we put on our faces that makes us so bad at noticing the changes in facial colour. Maybe faces pale with fear are indeed green as Homer describes them, but we just can't see that.

Aug. 18 2015 02:16 AM
Alby from Los Angeles, California

My son loves this episode and we've listened to it a million times now.

In the segment about the sky being blue, I started to wonder if perhaps when children ask "why is the sky blue" they are not in fact asking for a scientific reason but rather "why you are saying the sky is blue?" as in "I don't perceive the sky as blue... why do you keep saying it is blue?"

I find myself staring at the sky a lot now (which is always cloudless in SoCal) and trying to SEE it and not assign it to be blue. Just trying to be objective about what the sky might "really" look like. Have I just learned to accept that it is blue? What do children see?

Jul. 15 2015 07:53 PM
Virginia from Louisville KY USA

So does this explain why we have strange tree names like "Redbud?" Because the buds on a Redbud are light purple!

Jun. 21 2015 01:45 AM
Phil from Washington, D.C.

I found this article on Alma Deutscher playing the violin...

May. 19 2015 04:00 PM
Xander from santa barbara, CA

The order of discovery is along the color spectrum starting with short waves (red) and leading to longer waves. It seems to me we grew more able to see longer waves. A child looking up to the sky is seeing the longest waves we can see, and possibly not able to process them yet. We know the spectrum goes beyond blue, but we can't see into it...yet?

May. 04 2015 01:05 PM
Julie xu

Essay of Xun Zi (Hsun Tzu) "On Learning"475-221 B.C.The dye extracted from the indigo is bluer than the plant
Your claim in the show is most interesting, but in fact you need full fluent native speakers to find out your claim, because in Chinese it self, we have words of blue in different writing in different times of reflection of emotions. Such words in visual as 青 苍 碧 绿 蓝. And the above line have great background story about multiple stories.

Apr. 26 2015 01:10 PM
Richard from Boston, MA

Wasn't Homer blind? Not color-blind, but sightless-blind? His colors must have been what others told him, or some internal association he made on his own.

Apr. 23 2015 10:11 AM
laylage from brooklyn

can someone who knows greek speak to the fact that homer uses "wine-dark" not "wine-colored"? the deep sea does hold light like a red wine... "wine dark" evokes a luminosity/opacity, not necessarily a color. i always loved that homer's sea is wine-dark: mysterious and heady. the adventure depends on setting sail over it, just as the tales were originally told while drinking wine. pour a cup, the tale commences, we all set sail over the wine-dark sea.

Apr. 21 2015 12:22 PM
Diane Levine from Los Angeles, CA

I was doing a big, difficult jigsaw puzzle with a section of blue river. The blue pieces all looked the same to me until I noticed that some were "dark blue", some "medium blue" and some "light blue". Once I had established those linguistic labels, the pieces (that had all looked the same before) fell obviously into one of the three categories. I understand exactly the dilemma of the Himba who couldn't pick out the blue square!

Apr. 20 2015 11:33 PM
Kailey Smeltz from United States

I remember being young and not understanding that the sky was blue. I remember looking at a crayon called "sky blue" and thinking, "huh? Really?" It was interesting that she said white because I can relate to that. I also wonder if I am a tetrachromat. I am interested in doing research on this! =D

Apr. 20 2015 12:41 AM
ROZALINA GUTMAN from Berkeley, CA, United States

The remarks of neuro-psychologist Jules Davidoff and linguist Guy Deutscher on the color of BLUE were very resonant to my personal heritage. In my native Russian there are TWO distinct words - one for LIGHT BLUE - Голубой (pronounced - golu'boy) and another one for the DARK BLUE - Синий (pronounced - 'siniy). Indeed, they look like two very distinct colors and are always referred in Russian as such. (Notably, there are no similar verbal distinctions for the shades of other colors in Russian.) Maybe?.. the absence of this distinction in English (not as nuanced language as some Slavic languages) influenced little Alma's hesitation, since the word BLUE is too broad to describe both - the color of the sky ("whitish" blue in her description) and the distinct dark blue color of the ocean as it appears to us to be the color on the photo of Earth from the space etc.

I really enjoyed this amazing segment on the human visionary perception of colors! I am Russian-trained music educator, interested in brain/music perception aspects and appreciate this program's exploration of human senses' interpretation and its evolution (what an unexpected discovery!) - throughout the history of the humankind, along with the neuro-anthropological take.

I appreciate the notion about the combination of nature-nurture, in order to activate the unique ability of distinguishing color nuances. Those creators of educational policy and administrators who should be "assisting" arts educators should listen to this program (and be ...tested (-; on their full comprehension of its highly important content and its implications too). Also I hope the next exploration would extend into music and human auditory perception in a similarly intriguing ways. Again, thank you for this revealing and inspiring production!

Apr. 19 2015 11:39 AM
Michael Antonoff from New York City

Per above link, apparently "blue eyes" is mentioned more often than brown eyes or green eyes over hundreds of years of literature.

Apr. 18 2015 06:13 PM
Ken Gorfinkle from United States

I was deeply moved by the French existential novelist, Andre Gide's "Pastoral Symphony" in which color is described to a character who is blind, according to the instruments in Beethoven's sixth symphony.

Apr. 18 2015 12:13 PM
aeea from United States

i have a feeling Tibetan language falls into another pre-modern language that doesn't have a true color for "green" (as separate from "blue"). in Tibetan, many noun-forms take on the ending "po". this true of all major colors (red: "mar-po"; white: "kar-po"; black: "nak-po"; yellow: "ser-po"; blue: "ngon-po")... conspicuously "green" is "jang-khu".

if we do some digging, we have a reference to grass, or literally, "the blue color of wheat or barley". in other words, "green" is defined in old dictionaries as the color blue that wheat or barley is (as its growing, not after its dried, obviously).

meanwhile, "blue" is defined as "the color of the sky" and "the color of grass".

if i had to guess, the lexicographers of early Buddhist translation may have coined the term "green" in order to translate texts that referenced a "green" color, different from "blue", in their iconography...

also of interest, i've had conversations with modern-day speakers where "blue" was used to describe something "green"...

Mar. 04 2015 01:08 AM
Carol B from Florida

Perhaps Homer was color deficient. The first time a friend of mine with color deficiencies saw the deep sea on a Caribbean cruise, he was mesmerized by the color of the water, which looked, to him, like his favorite-colored thing - red wine.

Mar. 03 2015 11:39 AM
Janice from Israel

This is an interesting article, but I beg to differ with the author on a couple of things. Perhaps the modern Hebrew word for "blue," "kakhol," didn't exist in ancient times, but the ancient Hebrews had "tkhelet," "turqoise" or "light blue. It was made from a certain mollusk, usually thought to have been the Murex snail. It is mentioned in the Bible.

Also, the Minoan palace frescoes at Knossos frequently used blue. As did the frescoes at Santorini.

Mar. 03 2015 08:10 AM
Benji Adams from Decatur, GA

I had a thought on this. The massive eruption of Thera, a volcano in the Mediterranean Sea, took place around 2,000 BC. It was one of the largest eruptions in known history, may have sent so much soot into the atmosphere to darken the world. Krakatoa did so for years after it's eruption and Thera was 3x as large. Though I don't think it could have darkened it for centuries or millennia. I'm not any kind of expert on this.

From Wikipedia on Krakatoa, "The eruption darkened the sky worldwide for years afterwards, and produced spectacular sunsets throughout the world for many months. British artist William Ashcroft made thousands of colour sketches of the red sunsets halfway around the world from Krakatoa in the years after the eruption."

Maybe the sky was different back then in some way that blue was filtered out?

Mar. 02 2015 01:13 PM
Kelly from Philadelphia

Isn't Rama described as blue in the Ramayana? That's from the 5th century BCE. How ancient are we talking about?

Mar. 01 2015 12:27 PM

I read a reference to this on an article on Business Insider. I think there is confusion between the ability to see blue and the existence of a noun to define the color. It is not that Greeks had no capability to see blue and other populations in a short amount of time could develop it. Also what about the possibility that Homer might have been color blind?

anyway here is my comment on BI

I do not believe this article is very accurate. The Romans had the word "caerulean" for blue. and they came just a few centuries after the Greeks. I believe it is harder to create blue pigments and even among flowers blue does not seem as common as other colors. Radiolab dilutes and sensationalizes information. a quick search for "blue" on Wikipedia demystifies much of the content of this article: "The ancient Greeks classified colours by whether they were light or dark, rather than by their hue. The Greek word for dark blue, kyaneos, could also mean dark green, violet, black or brown. The ancient Greek word for a light blue, glaukos, also could mean light green, grey, or yellow.[14]

The Greeks imported indigo dye from India, calling it indikon. They used Egyptian blue in the wall paintings of Knossos, in Crete, (2100 BC). It was not one of the four primary colours for Greek painting described by Pliny the Elder (red, yellow, black and white), but nonetheless it was used as a background colour behind the friezes on Greek temples and to colour the beards of Greek statues.[15]
The Romans also imported indigo dye,"

Mar. 01 2015 11:54 AM

who is the artist covering blue moon at the end of the program?

Feb. 28 2015 10:10 PM

Same Vietnamese, the word "xanh" means both green and blue. So now we have to add "sky" or "leaf" to that word to differentiate blue and green respectively.

Feb. 28 2015 07:27 PM
Ellen Kudlicki from United States

In listening to this, I was struck by how the color blue-difficult and expensive to achieve in paint-was used in two very contrary ways. In the first way, the Etruscans midway through their civilization had blue skinned demons that seemingly brought about ominous events. Later, during the Renaissance, the use of lapis lazuli to create a heavenly blue reserved for the cloak of the Virgin Mary. Blue in Islam is used for tile glazes and interior decoration for mosques. This gets back to the core of what I ask my painting students-how do you know the red or blue I see is the red or blue you see? How much of our naming of colors is simply a product of habit?

Feb. 28 2015 03:13 PM
Claire L from Corinthos, Greece

I found it odd that Homer didn't mention the colour blue in the Iliad. I don't recall this while reading it in high school, but perhaps I'll have to read it again. Nevertheless, it is said that he may have been blind, but I do not think that is confirmed. He did live though a long time after the alleged date of the Trojan Wars (~1250 BCE) and I find it strange your claim that people didn't know this colour because it is present in frescoes in Santorini's Akrotiri dating back to 1650 BCE where the sea is blue. Granted those where buried when the volcano erupted, but if people knew and painted the sea blue, why wouldn't they know the sky's blue? The Minoan civilisation also had frescoes painted in blue backgrounds for the sea and sky.

Jan. 10 2015 05:02 AM
o.r. from Israel

The color blue existed in ancient hebrew: the word "Tchelet" mentioned 49 times in the hebrew bible. In modern hebrew the word "Tchelet" mean "ligth blue", but in the bible it means blue or turquoise (see here:
At the Mishnah ( there is even a distinction between diferent shades of blue...

Dec. 11 2014 09:38 AM
ElveeKaye from Arizona

I have read that many African tribes consider the sky to be white, not blue. When someone suggested it is blue, a tribesman (I forget which tribe, specifically) looked puzzled and said, "Well, I guess it is," probably just to humor the silly white man.

Dec. 08 2014 11:06 AM
Maya Pardo from Brevard College

I've read the Odessey in highschool, and I honestly dont remember these descriptions.

Dec. 05 2014 03:49 AM
Jacob Ray from Brevard College

I can't believe how our eyes have evolved just in recent time to see the color blue. I find it funny how most people find the color blue the most attractive as well being that it is the most recent color we are able to now see.

Dec. 03 2014 03:34 PM
Natalie Whitton from Austin, TX

Have you ever come across a word or piece of information that you have never heard of before, and suddenly, you start to see it everywhere? Maybe it's a cool bank you found or maybe it's the name of the company of your best friend's father. And the startling thing isn't the word or sound, but the difference in the frequency of you hearing it. This is called the Baader-Meinhof, or Frequency Illusion, effect. Once your brain is aware of information, it becomes easier to pick up the information outside. Now this is what really is in a name, the power of awareness.

This is a good analogy to the study with the Himba tribe by jules Davidoff. They physically saw the blue, but were not able to notice it. Guy Deutsche's daughter Anna saw the blue sky, but wasn't able to put a name to it, almost as if it didn't exist.

On another note, this episode reminds me of the episode where Doctors were asked to see if some x-rays showed signs of abnormalities, such as cancer. The real test was to see if the Doctors could spot obvious picture. The x-rays actually had pictures of gorillas on them. The doctors were focusing on looking for abnormalities, and a good percentage of them didn't notice the gorilla. A person who wasn't trained to see abnormalities in x-rays and to look at an x-ray with life and death deliverance might just see the gorilla.

Dec. 03 2014 01:47 AM
Dave L from Oakland, CA

A very entertaining story that raises salient questions about the role of mental processing and learning in sensory input; however, Occam's razor suggests an alternative hypothesis: vitamin A deficiency, which could result in a loss of the ability to see blue (according to Benjamin Backus, an Associate Professor at the Graduate Center for Vision Science at SUNY College of Optometry in this article about some whacky self-experimenters trying to see infrared by altering their diets).

Similarly, very young children may not have physiologically fully developed eyes. These effects would be worth looking at without the rose-colored glasses.

Sep. 11 2014 10:12 PM
Dave L from Oakland, CA

A very entertaining story that raises salient questions about the role of mental processing and learning in sensory input; however, Occam's razor suggests an alternative hypothesis: vitamin A deficiency, which could result in a loss of the ability to see blue (according to Benjamin Backus, an Associate Professor at the Graduate Center for Vision Science at SUNY College of Optometry in this article about some whacky self-experimenters trying to see infrared by altering their diets).

Similarly, very young children may not have physiologically fully developed eyes. These effects would be worth looking at without the rose-colored glasses.

Sep. 11 2014 10:11 PM
Helen Batchelder from Harvard Massachusetts

Regarding the blue sky: the sky is the sky. It's an entity. It's object that hovers over all, an an omnipresent god, enabling us to comprehend the ideas of omnipresence and permanence. Blue - cyan - is fleeting and requires us to open our eyes to see it. When we do, the sky may be clouded over, or full of water droplets, or splashed with sunset or tinted with sunrise, or fires, or smoke. It is the sky that is the sky, and the sky is not blue, blue is blue. Is this why children ask why the sky is blue? With some kind of innate understanding that 'blue' does not describe the sky?

Jul. 23 2014 03:34 PM
TBR68 from Toronto

This might be too much of an exotic answer to this "dilemma" but when I heard this it immediately made me think of this podcast.

According to their evidence, the sky may have, indeed, not been blue.

May. 18 2014 04:59 PM
Amber from UT, USA

this is more than a bit late, but as I missed seeing it anywhere in the comments: Welsh also has blue/green "confusion" (by English speakers' understanding of the words.) It is moving there, but historically many things we would consider blue were lumped together with things we consider green.

Mar. 18 2014 03:53 PM
J. Craig from Connecticut

As a teacher studying young minds I found your program enlightening. (sorry!)
You only mentioned the Egyptians when referring to the development of blue pigments. The Chinese had developed blue early on as well as cited here:

Han purple and Han blue (also called Chinese purple and Chinese blue) are synthetic barium copper silicate pigments developed in China and used in ancient and imperial China from the Western Zhou period (1045–771 BC) until the end of the Han dynasty (c. 220 AD).[1][2] (Wikipedia)

Another person who studied Homer was Julian Janes (The Origin of Consciousness in the Breakdown of the Bicameral Mind [Julian Jaynes, 1982] ) who claimed that the Homeric brain was bicameral and each side of the brain communicated independently yet the right brain was mute. The left brain served as the interpreter. In the case of color another level of complexity is where do the perception of colors lie in the brain and then how are they interpreted by the language center?

Jan. 29 2014 05:34 PM

To Terrence from NY: the original Homeric greek text is: "ἀμφὶ δὲ κῦμα
στείρῃ πορφύρεον μεγάλ᾽ ἴαχε νηὸς ἰούσης" and the word "πορφύρεον" stands for purple in modern greek. We may never be sure what the exact color Homer and the ancient Greeks had in mind with the word 'πορφύρεον'. Generally speaking, there will always be ambiguity about any word for color in the ancient cultures, as different minds percieve colors in different ways even today. We might guess from the noun κῦμα=wave that Homer meant 'blue' but we can never be sure. Another example of color controversy in ancient times is the 'red' color of star Sirius, a distinctive white-blue star.

Sep. 17 2013 12:59 AM
Jaymz Onion from Augusta, Ga

I am an artist. I have successfully trained many people in the art of mixing and matching colours - most intersestingly, those who are classified as colour blind. In a nut shell, I tell them that colour is only in the way your mind perceives the photons; the object isn't green, the word is 'green'. I will now be following up on the research delivered to us in your program to more adequately convey this concept to my students and peers.

By the way, I'm simply fascinated by the idea that there exists no reason to name a colour until we desire to recreate it, either in art or desriptive language. I'll have to chew on that for a while.

Sep. 10 2013 03:54 PM
Oneye from USA

Why isn't the sky blue?


You spent a whole hour on the radio and never got there. You need to do another show, with me.

The professor's 2 year old was more correct than you. You never recognized her wisdom. The sky isn't blue. If you don't know the word for cyan, and most don't, white is very good choice, it is in fact, the second best choice, much better than blue.

The colors of the rainbow are NOT ROYGBIV but ROYGCBV, ending in Cyan-Blue-Violet. Indigo is blue, deep blue, indeed rare. Violet is even rarer.

Paul Simon sang of Kodachrome skies. I did Newton's experiment with film. Fujichrome reproduced the order faithfully (if somewhat saturated). Kodachrome switched Cyan and Blue! So with Kodachrome you got BLUE SKIES.

The subtractive color wheel (with compliments) are

M (G)
C (R)
Y (B)

Where M=magenta.

Magenta is NOT violet. But Magenta CAN be seen in nature, not in the rainbow (since blue and red have to overlap) but in the brockenbow (optical glory).

What then is the compliment of violet? Ahah!

To see a complement, stare at a very bright splotch, then flick you eyes to black. Try it with violet!

If there were a tetrachromat, it would be violet.

Sep. 09 2013 07:55 PM
Mary Roth from Ann Arbor, MI

When understanding fails, turn to the poets...

Robert Frost - "Fragmentary Blue"

Why make so much of fragmentary blue
In here and there a bird, or butterfly,
Or flower, or wearing-stone, or open eye,
When heaven presents in sheets the solid hue?

Since earth is earth, perhaps, not heaven (as yet) -
Though some savants make earth include the sky;
And blue so far above us comes so high,
It only gives our wish for blue a whet.

Mitchell Goodman - "Down from the High Places"

High up there
we could look
down into it, up
into it, around, it was
colorless, called blue,
blue - allow it to
swallow us, follow us
down the dirt road in-
to the hidden field of
trees where the sun
comes to break dark
bowl and drink night.

Sep. 09 2013 02:27 PM

On another note.. The Japanese word you speak of is AO, which meant green and later implied BLUE as well, now in modern times it is used for blue.. They did not make a NEW word SPECIFICALLY for GREEN until MODERN TIMES, essentially blue and green were the SAME THING. The word for green is now Midori.

Sep. 09 2013 01:31 PM

Just finished a great novel, "Sacre Bleu" by Christopher Moore based on the color blue. His take is very intriguing set in the 1890's in Paris using impressionist artists and their involvement with that rarest of colors. great read.

Sep. 07 2013 03:24 PM
AdamH from NYC

It seems likely that ancient cultures could distinguish the color blue as indicated in the amazing Minoan frescoes that date back 1000s of years.

Sep. 07 2013 01:02 PM

I see quite a few comments already about the fact that Japanese is a contradiction to the statement that blue is always the last color to develop in a language. Japanese had the word blue exclusively until they made contact with the west. Blue is still used to refer to a lot of the shades of green in nature but the sky is clearly blue where as certain artificial greens and lighter color greens are definitely green. But, that's only in modern usage historically there was no color green.

Jul. 20 2013 03:46 PM

The Exodus mentions blue Exodus 25:4 number 4:6 Ezekiel 23:6

Jun. 16 2013 10:47 PM
Truthful Nacho from Earth

We assign colors to people according to sex as well. The effect of this is highly damaging, especially since female is assigned "pink" aka not a color in the official rainbow. Coloring babies or children by sex is a "tradition" which amounts to abuse in the young mind, just like all these experiments are.

Experimenting with the head of your own baby mama's kid: A requirement to enter the upper echelons of science dudery.

I also think the official rainbow has 7 colors because there are 7 steps in an octave (STEPS NOT NOTES, YES). "

Each color corresponds to a real frequency. To say "maybe we all see different colors but think we're seeing the same thing because our words to describe the different perceptions actually match" is to start a slippery slope to post-modernist (no pomo!) thinking. The colors, though ones calibration between them may differ from the next person's, are not arbitrarily PLACED. The spectrum has an order. As in, red comes first and then orange and then goldenrod and then buttercup and then yellow, and then green so on and and so on as the frequency gets higher.

May. 30 2013 04:42 PM
Val from New York

A mighty big assumption is being made here, and that is that human beings, as well as their consciousness and their perception, have remained the same throughout history and evolution. With rising consciousness, our ability to perceive also evolves and becomes more subtle. We know that animals see in black and white. We should also theorize that previous humans did as well with color becoming more and more prevalent as consciousness developed. To Homer, the color of the ocean WAS very similar to the color of oxen. And, differentiating blue from green has to be one of the most recent stages in this process. Many people STILL have problems differentiating the two. Is "aqua" blue or is it green?

Apr. 10 2013 01:08 PM

There's a Korean word that describes both green and blue as well, but it's the opposite of what was mentioned in the podcast as they're both considered 'bluish' instead of green. The five traditional colors are Black, White, Red, Yellow and Blue, and there is no native word that's specific for 'green.'

Apr. 09 2013 07:11 PM

whoah this blog is wonderful i love reading your articles.
Keep up the good work! You know, many persons are searching around
for this info, you could help them greatly.

Mar. 07 2013 12:16 AM
RMcDinGa from Macon, Ga.

When I was a young & foolish teenager during the hippie movement and the age, or adolescence, of the "Evolution of Rock", questions like this one were a part time hobby of a man with some depth, Timothy Leary"! The reason I asked about this, in my opinion, is because labeling is so judgmental, and serves very little purpose if any!
I believe one day there will not be this need for the using of groups in order to make some validity of the act of elitist self righteous members within society to make some impression with one's ego as they were able to accurately place someone who may have just needed someone to talk with! A potentially great experience never contemplated!! What a drag!

Feb. 19 2013 12:53 AM
Aston from New Zealand

Why is it that people keep bringing up the bible (and even the new testament) as if the bible is the oldest book around?

The new testament is pretty recent, having been written at around 200CE. The old testament was written likely around 700BCE, maybe even later.

Language and literature existed some millennia before the old testament.

Jan. 18 2013 06:58 AM
Scott from Austin, TX

This podcast cleared up a mystery! I often work in West Africa among the Zarma people, who speak a dialect of Songhay. When I was learning their language, I was amazed that they did not call the sky blue -- they said it was white! There is a word for blue, but the history of their language is not well documented and I don't know how "modern" the word is. When I said to people I thought the sky was blue, they would look at me funny and say something like, "Well, ok, I guess it is ... sort of." To be fair, the sky is rarely a deep blue there--the dust from the Sahara often blots it out to a pale blue. Also, they tend to call all light-colored objects "white". Still, it was interesting to hear they are not the only ones who think the sky is white.

Dec. 02 2012 09:40 AM
Mittleman D track from Los Angeles, CA

In your segment on colors, you claim that the Odyssey never uses the color blue. In Robert Fagles translation of the Odyssey, describes Odysseus " Clutching his flaring sea-blue cape in both powerful hands"(Book 7 Line 100). Is this just a translation error?

Nov. 26 2012 03:16 PM
Rhys Maclean from Australia

“When Homer lived is unknown. Herodotus estimates that Homer lived 400 years before Herodotus' own time, which would place him at around 850 BC;[1] while other ancient sources claim that he lived much nearer to the supposed time of the Trojan War, in the early 12th century BC.[2] Modern researchers appear to place Homer in the 7th or 8th centuries BC.”

Homer referred to the sky as bronze.

In 1646 BC a massive volcanic eruption, perhaps one of the largest ever witnessed by mankind, took place at Thera (present day Santorini), an island in the Aegean not far from Crete. The explosion, estimated to be about the equivalent of 40 atomic bombs or approximately 100 times more powerful than the eruption at Pompeii, blew out the interior of the island and forever altered its topography.

Is this a clue to pinpoint the period of Homers life?
Just a random thought..

Oct. 31 2012 07:58 AM
Tani from Canada

It's also interesting to me that Russian has two words for blue, голубой (goluboi) which is light blue and синий (sinii) which is dark blue, but they don't think of them as the same color, which of course is how English speakers think tend to think of them. I don't know what blue was called in ancient Slavic languages or Old Church Slavonic, but it would be interesting to investigate further.

Oct. 05 2012 12:09 AM
to from Raleigh

what is lapis lazuli and indigo? Two highly prized "blue" things of the ancient world.

Oct. 04 2012 12:34 PM
Michael Burch from Emory University

As crazy as it sounds, Gladstone's theory of how people came to see color isn't as stupid as you might think. Lamarkisism, the idea that traits evolved by the strain of a parent passed to a kid (e.g. a giraffe strains its neck to reach leaves and therefore little by little its neck grows with the generations), was very popular at that time. Gladstone wasn't spouting off a crack-pot theory, but rather applying modern science. It doesn't make his hypothesis any less wrong, but I figured I would defend him.

Oct. 02 2012 06:10 PM

today i learned about Methemoglobinemia and immediately thought of this Radiolab segment. here's to another example of the color blue in nature!

Sep. 20 2012 03:49 PM

I have often brought the subject of this episode up in discussions with friends. What I find interesting is the occasional hostile or defensive reaction of a small number of people - as if somehow the idea that "blue" was a latecomer to a language upsets their world order. Others on the other hand see it as an interesting thought experiment and want to explore the idea further.

Sep. 18 2012 12:00 PM
Misti Wudtke from Ohio

Excellent episode, as always!

I have a comment on rainbows and specifically human perception thereof. I'm obsessed with Norse myth and, while reading Snorri Sturluson's Edda, was struck by the description of the rainbow bridge Bifrost (called Bilrost in other sources):

"You must have seen it, maybe it is what you call the rainbow. It has three colours and great strength and is built with art and skill to a greater extent than other constructions..."

Nowadays we of course think of rainbows as having more than three colors; apparently medieval Norsemen did not. I don't know much about Old Norse words for various colors, other than that the same term was used both for blue and black ("blar"). As I understand it, Harald Bluetooth (yes, the king for whom Bluetooth technology is named) could as easily have been called Harald Blacktooth, probably just because he had a diseased tooth.

Thanks for the show & keep up the good work!

Sep. 06 2012 01:22 PM

I really enjoyed this podcast. The song at the end of the podcast
reminded me of an excerpt from one of my favorite books. In "Krakatoa" by Simon Winchester
he mentions a "blue moon" that people witnessed every night for months.

Here is what NASA says about the subject of a "blue moon" ...
When the Indonesian volcano Krakatoa erupted in 1883, people reportedly saw Blue Moons every night, according to NASA.

Krakatoa's ash was the reason. Some of the plumes were filled with particles 1 micron wide, about the same as the wavelength of red light. Particles of this special size strongly scatter red light, while allowing blue light to pass through. Krakatoa’s clouds thus acted like a blue filter.

Sep. 01 2012 10:25 PM

I wrote a blog post about this and quoted the comment by Elan May 28 and wanted to acknowledge the show and Elan's comment

Aug. 11 2012 12:53 PM

On page 445 of my 1994 "Stone Edition Chumash" (Torah, with Hebrew, English, and commentary), is Exodus, Chapter 25, verse 3-4, which says (in English):

"This is the portion that you shall take from them: gold, silver, and copper; and turquoise, purple, and scarlet wool; linen and goat hair"

And the commentary says about the word it translates as "turquoise":

"[Techelet] -- And turquoise...wool. The first three items in this virse are different colors of wool. Techeilet, the first of the three, was madde from the secretion of a rare amphibious animal known as chilazon, whose exact identity has become forgotten with the passage of time. The talmud describes its color as similar to that of the sea.

Please note: it directly says that the Talmud describes the color that is used to dye the wool in the Torah/Hebrew Bible, as a color similar to that of the sea.

I loved all the other parts of this Radiolab. But I really cannot understand why you said that the color blue was not in the Torah. It is, and it relates both to natural things (like the stone that G-d's throne sits on, and the gem in the priests' ephod) and human things, like parts of the fabric decorations on the priests' garments, and the fringe on the regular garments.

Who told you that "blue" was not in the Torah?

Aug. 05 2012 07:42 PM
Stephan from Sacramento, CA

Any idea where I can get that rendition of Blue Moon?

Aug. 03 2012 02:24 PM

The linguist in this piece seemed to start with observing (whether rightly or wrongly) that his samples of written texts did not have words for blue.

My concern is that he leaped from there to an assumption that early man did not have words for blue either. Humans had been illiterate for many thousands of years before learning to write.

Another Foxconn job?

Aug. 02 2012 06:46 PM
L W Calhoun from Atlanta

What color is the sky ? Such a dumb question !

When Guy Deutscher's daughter, Alma, said the color of the sky was 'white', she may have been referring to the clouds, which, other than aircraft, are the only observable objects in the sky.

After all, "What color is the sky ?", is an illogical question. Apparently, Alma understood that even if her physicist father didn't. The sky is mostly void, therefore, it can't have a color.

Jul. 31 2012 05:04 PM
Tsafrir Mor

Thanks for an entertaining program. However, there were many statements that were were nonchalantly passed as if they were facts. For example, statements regarding the absence of blue in the Hebrew Bible. It is true that the root כחל on which the Hebrew word for blue כחול (Kachol) is mentioned only once (Ezekiel 23:40) in describing application of eye shadow, possibly (but not certainly) of bluish tint as can be seen in Egyptian art. However the Hebrew word for light blue תכלת (techelet) can be found numerous times. Most ancient authorities understand this word to mean (light blue) and refer to a dye produced from the hemocyanin-rich (blue) blood of marine molluscs.

Many of the "authorities" cited read much of the quoted texts in translation. The authors talk about the lack of colors in Homer's epics. The phrase "rose-fingered Eos" (~Pink Dawn) appears hundreds of times in Odyssey. So Homer, who according to legend was totally blind anyhow, at least mentions one other color besides black and white. For example the references to Homer's Odyssey spoke of the cyclope's purple sheep and of black wine. What does the original say? Because I don't know classical Greek, I turned to several (Hebrew and English) translations and they speak of "dark" sheep's fleece and the wine is referred to as black, but this become quite understandable as several verses later it is described that this highly concentrated and strong wine is diluted 20 fold (!) before being drunk as "red" wine. It is clear that the wine is so thick that it is practically black.

So RadioLab weaves a compelling narrative, but how accurate is it?

Jul. 30 2012 01:45 AM
Dianne from San Diego

I can't figure out why the focus of the "blue" discussion was limited to literature. Was there no blue in ancient visual art? Certainly blue shows up in minerals and gemstones. Didn't the ancient Egyptians create a dark blue glass? You no doubt have greater expertise in this area that I would, but I thought it was a curious omission. I love your show but this one left me a little dubious about the conclusions reached since the basis for the conclusions seemed to be based on limited evidence. I can easily be wrong, of course. Art history was not my area.

Jul. 29 2012 03:33 PM
Jane Gen Cassidy from San Diego

Dear Mr. Krulwich,
Re: Colors
Your work in Radiolab's episode on colors is as usual; marvelous.
As an artist, color is the most ephemoral thing yet.
Thank you for delving into this subject matter so that all listeners, artists and everybody else can relate to the mystery that is color.
Jane Cassidy
P.S. Mr. Krulwich; are you married?

Jul. 28 2012 07:38 PM
Ledette Clopton from Minnesota

I regularly enjoy listening to Radiolab and did today as well when I heard your piece about the color blue. I studied linguistics and some philology many years ago, and even though I've forgotten a lot and it was in the past, I noticed some lacunae, namely mentions of Sapir, Whorf, and Lakoff (and Liberman). Further, the word blue is attested in Germanic languages in texts that predate the Old Icelandic sagas mentioned in your piece. I missed the last two minutes or so of your piece due to a phone call. Perhaps you dealt with all of these issues then. In any case, thank you for the program!

Jul. 28 2012 05:07 PM
dl from new jersey

A search of the word "blue" in the bible comes up with numerous uses of the word, particularly regarding the colors of the curtains of the tabernacle and the priestly garments. For starters, Exodus 26:1: "you shall make the tabernacle with ten curtains and purple and scarlet yarns..." and 26:4: "you shall make loops of blue on the edge of the outermost curtain..." Mistranslation? would love an explanation.

Jul. 28 2012 12:51 PM
Dena from NY


Not to be a pain, but blue is mentioned in the original hebrew bible in numbers 15:38.

דַּבֵּר אֶל־בְּנֵי יִשְׂרָאֵל וְאָמַרְתָּ אֲלֵהֶם וְעָשׂוּ לָהֶם צִיצִת עַל־כַּנְפֵי בִגְדֵיהֶם לְדֹרֹתָם וְנָתְנוּ עַל־צִיצִת הַכָּנָף פְּתִיל תְּכֵלֶת

that last word, techelet, being a specific blue color made from the dye from a certain kind of shellfish.

I would love to hear a response on this.

Jul. 27 2012 10:51 PM
Nicolas Collignon from copenhagen

to the comment above: read this article about colors! it's very well explained.
'Blue and green are similar in hue. They sit next to each other in a rainbow, which means that, to our eyes, light can blend smoothly from blue to green or vice-versa, without going past any other color in between. Before the modern period, Japanese had just one word, Ao, for both blue and green. The wall that divides these colors hadn’t been erected as yet(...)' and 'One of the first fences in this color continuum came from an unlikely place – crayons. In 1917, the first crayons were imported into Japan, and they brought with them a way of dividing a seamless visual spread into neat, discrete chunks. There were different crayons for green (midori) and blue (ao), and children started to adopt these names. But the real change came during the Allied occupation of Japan after World War II, when new educational material started to circulate. In 1951, teaching guidelines for first grade teachers distinguished blue from green, and the word midori was shoehorned to fit this new purpose.'

hope it helps!



Jul. 25 2012 05:46 PM
Kate from New Orleans

Really interesting podcast!! I just was curious though, if there was no word for blue and that correlated to not being able to see the color blue how were ancient greeks able to incorporate so much blue into their artwork?

Jul. 23 2012 02:28 PM
Kip from Angullara, Italy

This has made me think about things we see every day but "misname" the color or don't recognize as color. Italians call the yolk of an egg the rosso (the red). Yolks of farm-raised chickens are much more red- orange really- but not really red.
The example that comes to mind for me is the color of Caucasian skin, for which we have no real name. We say white, but I'm very white and I'm definitely not the color white. Maybe because of social dangers we avoid giving skin tones unique color names, but we accept and use very incorrect color names and generalize in our minds (I don't find yellow skin to be at all yellow, white to be white, or black to be black). Crayola named the skin-tone crayon peach, but, oddly, that crayon is nothing like the color of any peach I've ever eaten. Hmm.

Jul. 20 2012 07:26 AM
Tina from Florence, MA

I am still thinking about this episode - the development of color perception. I just got a smithsonian news article about "how ancient greeks named their puppies" and one of the most common names was Blue. So what does that mean? What kind of blue? Here is the link to the article.

Jul. 18 2012 09:58 AM
glassgirl from seattle

when people are in the sun a long time ( like surfers) their corneas go "yellow" and lose the ability to see purple and blue hues. ( ie why little old ladies try to get the yellow out of their hair and then go too far in the other direction and dye their hair blue or purple. to their eyes their hair looks yellow even when white. this would make sense in a desert environment ( where no sunglasses existed) or even in a predominately sunny blue ocean environment (greece). maybe this is part of the problem of ancient scholarly manuscripts- the author is most likely an adult and after years of exposure have gotten a yellow tint in their corneas and thus a filter that blocks blues and purples.

Jul. 18 2012 01:18 AM
Jed Stevenson

Others have noted Franz Boas' work on color, and the program highlighted the case of the Himba, but I was surprised that the classic work on color terms across cultures -- Berlin & Kay's 1969 "Basic Color Terms" -- wasn't brought up. They showed color chips to people in many cultures, and got them to name them. And by doing that, they established something similar to what was presented in the show as a process of historical evolution: that if your culture has 2 color terms, they'll be black and white, if 3, then red is added; after that there's more variation.

I'm not sure Berlin & Kay's data support the idea that blue is always last. But the collapsing of blue and green that Benjamin Buehler mentions in Japan was also noted among the Aguaruna people of the Peruvian Amazon; it's glossed as "grue". That's a good example of how langauge can slice up the visual spectrum into different categories -- which is what's going on when we name colors in general.

Jul. 17 2012 10:04 PM

I always really enjoy listening to RadioLab and this podcast is no different. The podcasts always leaves me thinking and pondering our world and our perceptions of it! My son is colour blind but only lightly so (so they say), having a difficult time seeing a difference between Dark Blue and Dark Green. So what does that say about my perceptions or my husbands? Do we really (all three of us) see colours so differently?

I know painting class really opened my eyes to colour... My teacher taught us to paint what we saw, paint with your eyes not your brain. There are no white clouds! I can never look at a cloud now and not see the greys,blues, violets and yellows. Often pinks and orange tinges too! These colours were always there but I would not have known how to paint them if it was not pointed out and forced to see! And this is after years of cloud watching for shapes or forms!

This broadcast leaves me wondering what colours are out there that we have not been guided to see yet? Where can they be found? I wonder about things like the various colours a bruise goes through before healing. There must be more examples of shifting colours that might lead to the discovery of new colours within our own visual range!

Jul. 14 2012 09:32 AM

It was mentioned that vedas did not mention of blue color,But in fact they do mention, it is believed that the Sun god(Surya) rides on seven horses each horse a representing a color of rainbow. Also there is this very interesting stotram the "suryanarayana suprabatham" which describes every stage of sun rise,set etc) in colors, you can find it at .
Hope this will help anyone researching this topic.

Jul. 13 2012 10:18 AM
b from nyc

@ Jim from Memphis: you are first citing a translation, so I wouldn't trust that too much, and if I remember they do talk about the bible and mention "in Hebrew". And second "a path that was as blue as the sky", isn't it a bit strange that a "path" is blue? Do you often travel on blue paths when you go hiking? Wouldn't it make more sense that the path was white and the sky perceived white as this time?

Jul. 05 2012 07:46 PM
Kester from London

"I wish there was just one more part to the three part colors episode of radiolab that launched into how neuroscience, anthropology, and linguistics explain how we attribute colors to feelings or states of mind."

Me too. I've blogged a little something about this actually:

As the RL piece notes, the blue-ness of the skies and oceans are so vast and ‘out there’ that they do not count as blue. So perhaps blueness has always been about the beyond, something slightly beyond the natural, and the immediately tactile. The blues are the blues because they can similarly not be easily communicated, not at first… and are a state slightly beyond language, beyond straightforward communication.

Just a thought... and what about 'Blue Movies'? Interwebs don't seem to know...

Jul. 02 2012 09:36 AM
Jim from Memphis

In Exodus 24:10, Moses begins the ascent of Mount Sinai to receive the 10 commandments. He begins the ascent accompanied by his brother Aaron, and 70 elders. They travel on a path that was as blue as the sky. So, they are familiar with blue, and they call the sky blue.

I have to conclude that my friends at Radiolab got this part of their story wrong, and it is a pretty important part of the story.

Jun. 30 2012 11:49 AM
Sam rosen from Austin, Texas

Thank you for the comment below is one. I was going to write to Radiolab to discuss the factual mistake of the Hebrew scriptures not having a word for the color blue. Sure, the color for blue in modern Hebrew did not exist in those times. But I think it's important because the conclusions made about blue either lose some argumentative power or a deeper look into Hebrew/Israelite religion could add to the discussion. Techelet is a perfect example. It appears In G-d's command to use this specific blue on prayer shawls, so it meant that the entire group used the same blue - which is a continuing rule today, though according to Talmudic sources, the animal that created this specific color blue is now extinct. Today, modern Jews use simple white threading, instead of an imposter blue.

Jun. 27 2012 04:17 PM
ultros from Oakland, CA

I'm geeking out a little bit today with thinking about the Hebrew Bible. After reading everyone's comments and spending an embarrassing amount of time digging through Strong's Concordance, here's a few observations about blue:
-- There are two blue-ish words used in the Hebrew, both of which have already been mentioned: sappir (5601) and tekeleth (8504).
-- Sappir is used almost exclusively in reference to the actual mineral sapphire or lapiz lazuli. It's often used in lists containing other minerals like diamond, turquoise, or chalcedony.
-- Tekeleth is used almost exclusively to refer to dyed fabric. Misha's link to wikipedia gives a good explanation about how this is a very specific dye made from shellfish. It seems tekeleth is used to specify the use of this dye. Also, Strong's defines tekeleth to mean "violet," and it is sometimes translated as "blue," "purple," or "violet."
-- As far as I can tell, neither the sky nor the ocean is ever called sappir or tekeleth.
-- The word "blue" never appears in the Greek New Testament.

Contrast all of this to red:
-- First of all, the Red Sea doesn't count, because apparently it's not called that in the Hebrew at all, but...
-- The word adom (122) and its various forms describe a whole variety of things: soup, animals, dyes, blood, wine, rashes. It's used in a broad way, like we might use it.
-- Red also appears in the Greek New Testament (purros #4450 and its derivations). It also refers to a variety of things.

So it does seem like the Hebrew Scriptures use the word "red" much as we would, but the words we translate "blue" don't seem to mean exactly what we mean when we say "blue." Anyway, totally fascinating.

Jun. 23 2012 06:31 PM

I was just going to comment on the blue traffic light in Japanese and I saw Benjamin's comment. Yes, we do refer to the green light as the "blue light", and when the trees are full of very healthy green leaves, we say the trees are very blue (青々しい). We see green and we have a word for green (midori 緑), but for certain items, we use the word blue, even when they are green. Unfortunately, I don't know why.

Jun. 10 2012 03:02 AM

Why make so much of fragmentary blue In here and there a bird, or butterfly, Or flower, or wearing-stone, or open eye, When heaven presents in sheets the solid hue? Since earth is earth, perhaps, not heaven (as yet)-- Though some savants make earth include the sky; And blue so far above us comes so high, It only gives our wish for blue a whet.

Fragmentary Blue by Robt Frost

Jun. 09 2012 09:50 PM

I find it odd that blue would be not noticed in Greece where it is a predominant color in skies and seas offset by the white of buildings. Maybe it's the opposite of the scarcity theory, too much of it everywhere made it uninteresting and unnoticed. And of the child who did not say blue for the sky, is it possible that she thought of sky as air and therefore colorless?

Jun. 08 2012 03:41 AM
Arlo from PDX

To those of you citing the blue things in the Hebrew Bible. The question at issue is not whether blue things appear, but that an actual word like blue is used to represent ALL blue things!

Jun. 07 2012 04:07 PM

@ vgbnd from Berlin

Just to make things even much more puzzling, when Homer does use blue, apparently he uses it to describe non-blue things, at least according to this random article I found on the internet:

"He also uses kyanos oddly, "Hector was dragged, his kyanos hair was falling about him". Here it would seem, to our understanding, that Hector's hair was blue as we associate the term kyanos with the semi-precious stone lapis lazuli, in our thinking kyanos means cyan. But we cannot assume that Hector's hair was blue..."


Jun. 05 2012 11:24 AM
Clark from Newcastle Australia

The argument about names for colours is reinforced by a review of surnames. In English we have plenty of Black, White, Brown, Grey and Green names, but there aren't a lot of Blues around. This topic interests me since my surname is derived from the Gaelic word 'gorm' for blue. However, when I looked into it, 'gorm' can mean blue or green.

Jun. 05 2012 06:57 AM

Loved this podcast! But agree with others about possibility of blue in the Bible... here is something to add to the discussion. Thanks to Wikipedia for some quick reference finding and for the online Strong's Concordance.

Another blue seen in the Bible is (: Strong's H5601 - cappiyr( סַפִּיר)), which is called Sapphire or Lapis lazuli ( "In antiquity and as late as the Middle Ages, the name sapphire was understood to mean what is today described as lapis lazuli." Schumann, Walter (2006) [2002]. "Sapphire". Gemstones of the World. trans. Annette Englander & Daniel Shea (newly revised & expanded 3rd ed.). New York: Sterling. pp. 102. ). Lapis lazuli is derived from the Persian word lāzaward, meaning "heaven" or "sky" , which means that the Persian's didn't call the sky blue, they called it lazaward...

With this in mind look at these two passages (Numbers are Strong's Concordance Ref #'s): Exodus 24:10 "And they saw 7200 the God 430 of Israel 3478: and [there was] under his feet 7272 as it were a paved 3840 work 4639 of a sapphire stone5601, and as it were the body 6106 of heaven 8064 in [his] clearness 2892."

Ezekiel 1:26: "And above 4605 the firmament 7549 that [was] over their heads 7218 [was] the likeness 1823 of a throne 3678, as the appearance 4758 of a sapphire5601 stone 68: and upon the likeness 1823 of the throne 3678 [was] the likeness 1823 as the appearance 4758 of a man 120 above 4605 upon it."

Jun. 03 2012 09:17 AM
vgbnd from Berlin

i found this episode very fascinating, thank you!
however, i immediately went on to search a couple of ancient texts, especially homer's odyssey and the bible. i can't find a single version online where there is no mention of the word 'blue'. (for homer there are always 7 or 8 occurrences). can anyone recommend a version where this is not the case? why there is 'blue' in the texts i find.
thanks a lot!

May. 31 2012 11:42 AM

Ah, incorrect. Purple or violet is the last color term that finds it's way into the lexicon, at least for the basic colors. (we'll leave peach and the rest to Bed Bath and Beyond) The first two are white/black, or warm/cold. Fact checking helps.

May. 30 2012 06:51 PM
Adam Green (yes, I know) from Guelph, Ontario

Really enjoyed this episode! To throw my personal experience into the mix... I'm a red/green colorblind male (Deuteranomalic, not Deuteranopic) that does science for a living and has particular trouble distinguishing blue / purple and also red and black when they occur in overlapping patterns (like on a fast-food menu board or a red laser-pointer on a power-point display). In both cases, but even more-so in the red/black case, I will fail to see the red at all until someone else points out that it's there. Then I'll be able to see it in my peripheral vision and then, shortly after that, I'll be able to make it out with some trouble when I look at it head-on.

I've noticed this for years and it lead me to take part in a few color-blindness studies. Each time, they confirm that I'm color-blind but often say that I'm the least color-blind in their study. So for me, I follow along a little with the hypothesis mentioned in the show, that I just don't 'see' the color until it's named and pointed out to me by someone else; then a switch gets flipped in my brain and I can see the red in the black or name the blue and the purple. Perhaps this stems from a slight physical vision deficiency reinforced with years of disuse as a kid. Over the past 10-15 years its become a bigger deal in my life and my brain is struggling to re-wire itself while still dealing with the deficiency? Who knows for sure, but that segment resonated with me. Thanks Radiolab!!

May. 30 2012 11:31 AM
Ariel from illinois

Given Deutscher's daughter's predicament with the color of the sky, are their any records of cultures who do describe a clear sky's color but decide it is other than blue?

May. 29 2012 09:19 PM
Elan' from Los Angeles, Ca.

I remember going to a panel discussion at San Diego Comic Con on coloring comics. I thought they would just go over coloring comics in Photoshop. Instead, we were given a slideshow of photos th lecturer, Steve Oliff, took.

He would point out how the green of those leaves were a little more blue than the green on the other leaves. That those two white wall, although painted the same were different colors because of the angle of the light and the orientation of the walls. Its just a little subtlety.

I didn't realize how much this discussion on coloring comics would have on me. After the convention was over for the day and everyone left the convention hall, I saw the most beautiful sunset! Like, I noticed how rich the pinks and oranges were on the clouds. The lavenders. The different shades of colors.

Every now and then I had to close my eyes because the colors were so overwhelming!

I saw the different shades of gren as we passed by the trees and the different kinds of concrete depending how much light bouned off that surface.

I have worked in tv and animation and I've been complimented for my eye for color and color correction.

I can believe that the sky was not "blue" until someone pointed out what blue looked like. And after you notice what blue looks like, what that color really is, you can't go back.

May. 28 2012 09:51 PM
Rick from St Paul

As always, fantastic podcast! Perhaps a take-off from this podcast is the lack of the color blue in ancient texts, including the original Hebrew Bible.

Maybe you can answer the question: how is it that our current version of the Christian Old Testament uses the word blue many times if the original Hebrew has no such word?


May. 27 2012 05:18 PM
Gal Haspel from MD

I also encountered the usage of blue for traffic lights in Japan during my visit. Three points:
1) the bottom light in the traffic lights in Japan (and in many other places) is indeed light blue and not green. Look at it more carefully next time you drive.
2) The Japanese perception of the delineation of green and blue is different than mine was. In part of my trip I ran many "what color is this?" conversations/ games.
3)Can Dr Davidoff travel to Japan with his 15 greens and 1 blue grid? I think the result will be interesting (e.g. "I don't see one different. I see two groups: five blues and eleven green")

May. 26 2012 11:31 PM
jj from brooklyn

words, perception, colors
a perfect example

this site has 3 videos (make sure to scroll down to see all 3)
each video describes one of the colors below the video
after watching the video try to guess which color

how we individually perceive and how we collectively perceive
one friend was upset wanting the correct answers
another friend was upset thinking they chose the wrong color
thought both responses were interesting....

May. 26 2012 10:06 AM
Jimmy Volatile

Obligatory XKCD: :)

Before I took my design education, bad kerning almost didn't exist for me.

May. 25 2012 03:55 AM

There is this one interesting fact about color perception in its association with a word or template so as to say.Just as different languages describe the three primary colors with different words and still are able to discriminate it, is it possible that our psychological perception of color is different from person to person ?
To be more precise what I feel red is someone else's blue feeling but we can't communicate it just because we have attached a standardized linguistic template to it. And if so are this feelings just templates that our mind attaches when we are still learning about our world as a child or is more strictly determined by our genetic makeup ?

May. 24 2012 11:06 PM
Amy Cannon from Pasadena, CA

Not "noticing" blue when a language has no word for it is almost perfectly analogous to something I learned studying Linguistic Anthropology as an undergrad: people rarely register the difference between _phonemes_ when it is not also a difference between _morphemes_.

Certain people who natively speak an East Asian language may have a noticable proclivity to confuse "L sounds" and "R sounds" when speaking English. Though such sounds _are_ indisputably different, they do not have a difference of _meaning_ in certain languages, making it harder to distinguish for someone who's native language lumps them together.

In English, there are aspirated and unaspirated "P" sounds, for instance, but to us, they all fall in the "P-sound" category, so we don't notice that there is a difference in sound, one that meaning might turn on in another language group. It would be just as hard to "see" as the difference between blue and green, though we can show through muscle contraction, mouth shape, etc. that they are in fact different sounds the world over.

May. 24 2012 08:29 PM
Michael from San Francisco, CA

At the end of the episode, we leaped into idiomatic expressions for "blue." In German, to be drunk is "I am blue" or "Ich bin blau" as opposed to being sad, as in English. I wish there was just one more part to the three part colors episode of radiolab that launched into how neuroscience, anthropology, and linguistics explain how we attribute colors to feelings or states of mind.

May. 24 2012 03:24 AM

Hi, that last comment is accurate. In Japanese the word that is now used for green actually came into use more recently than blue. Tree leaves for example are sometimes still referred to as "blue" and the traffic signal is always talked about as turning blue rather than green.

May. 23 2012 04:46 AM

In case anyone wanted to see the Himba experiment:
Amazing, what was missed in the episode is their amazing ability to differentiate greens - but have absolutely nothing on the blue.
So do our words shape us? Or do we shape our words....

May. 22 2012 10:57 PM

Why has no one brought up the auditory corollary to this? I am a native speaker of English. If a Spanish-speaker pronounces the sound "r" and the sound "rr," I can easily hear that there is a difference between the two sounds. However, when I am trying to speak Spanish, I often swap a flat "r" for the rolled "rr." Because interchanging "r" or "rr" doesn't alter the meaning of spoken English words, my brain just sort of glosses over the difference in the two sounds and lumps them into one category - "r." It's not until the difference in sounds is significant (in the sense that it *signifies* - that we have given it meaning) that we recognize the distinction. For example, in English, we recognize the difference between "l" and "r" as significant - "lice" is different from "rice." In some languages, the difference is not significant, so native speakers use the sounds interchangeably.

As for an example of language not reflecting distinctions in color, even though our senses perceive them, and how that is related to culture: A question for any fellow white North Americans reading this - what is the word you would use to name the skin color of people of African, Native, and South Asian descent? Brown. One word. One word, for a thousand gradations and distinct tones. We can see the differences, and if pressed, we can make distinctions (coffee, chocolate, etc), but in our minds, all of those skin tones fall into one category - brown. Now, a question for my fellow Americans (North and South) who are not white - how many words do you have for different shades of brown skin tone? Tons.

Those are just the tangents that this episode sent my mind spinning off into...thanks Radiolab!

May. 22 2012 10:29 PM

I was also going to comment that the Hebrew bible mentions techelet which is commonly considered blue although the Torah does not explicitly say it is blue. Rabbinic tradition is that is resembles the sea and the sky. Archeological evidence show that it's blue. Rabbinic literature also warns of fakes of a similar color made from a plant such as indigo. For more see: Thank you radiolab for another very insightful and thought provoking episode!

May. 22 2012 06:32 PM
Misha from Minneapolis

Just want to throw it out there that the Hebrew Bible does mention a special blue many times, in the form of Tekhelet:

May. 22 2012 03:12 PM
bob minder

do remember reading that the father of american anthropology, franz boas, wrote his doctoral thesis on the perception of color. how there are variations in cultures in how they divide the colors on the range up, the word for green begins a bit further into the green blue in this group in contrast to that, etc. and he focused particularly, i do believe, on the perception of the sea. makes me curious to know more. but i do believe he went on to focus on and live in northwestern native communities. the totem poles of some strike me as quite colorful, but i wonder about the colors in the world of the inuit? anyway....

May. 22 2012 01:44 PM
Benjamin H. Buehler

Does blue always come last? In my Japanese II class, we learned that the Japanese word for 'green (traffic)light', 青信号 (pronounced aoshingoo), actually translates literally to 'blue (traffic)light'. Our Japanese teacher said that this was because, before Japan's period of isolation from the rest of the world ended with Commander Perry's voyage to Japan, blue and green were actually considered to be part of the same category of colors. I would be interested to learn whether this is accurate, and if not, what the actual story behind the phrase 「青信号」 is.

May. 22 2012 01:09 PM

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