"The most merciful thing in the world..." H.P. Lovecraft writes in his horror story The Call of Cthulhu, "is the inability of the human mind to correlate all its contents." To be sure, if all our memories and perceptions registered in the mind equally, we should be like the unfortunate Funes of the Borges tale - completely overwhelmed by the sum of our experiences, unable to act. Yet, as Freud realized, we pay a price for this compartmentalization. The conflicts, urges, and passions that we sacrifice in the interest of present concern do not merely vanish. Like Cthulhu, they lie beneath the depths; in the apt phrase of The Fields of the Nephilim, "dead but dreaming". They call to us when our emotional stars are aligned, waiting for...