Robert kicks things off with a beautiful re-telling of a 2400-year-old love story from Plato, by way of Aristophanes, about the longing many of us feel for another half to make us whole. This ancient yearning gets us wondering whether the world around us is deeply and fundamentally symmetric, or...not. Zoe Keating's looping, lyrical cello scoring spurs us on our quest.

After looking for soul mates in Greece, we head to Princeton's Neuroscience Institute, where Lauren Silbert uses brain scans to try to zero in on what happens when two people click. In the process, she stumbles upon a subject who seems to be her brain double--and we go on a hunt for an Aristophanes-inspired happy ending. Joy Hirsch, a neuroscientist at Columbia, weighs in on our desire to pinpoint love in an fMRI lab.