And when one of them meets with his other half…the pair are lost in an amazement of love and friendship and intimacy, and one will not be out of the other’s sight…even for a moment: these are the people who pass their whole lives together, and yet they could not explain what they desire of one another. For the intense yearning which each of them has towards the other does not appear to be the desire of lover’s intercourse, but of something else which the soul of either evidently desires and cannot tell, and of which she has only a dark and doubtful presentiment.

—Plato, Symposium