The world is so big, so complicated, so replete with marvels and surprises that it takes years for most people to begin to notice that it is, also, irretrievably broken. We call this period of research “childhood.”

There follows a program of renewed inquiry, often involuntary, into the nature and effects of mortality, entropy, heartbreak, violence, failure, cowardice, duplicity, cruelty, and grief; the researcher learns their histories, and their bitter lessons, by heart. Along the way, he or she discovers that the world has been broken for as long as anyone can remember, and struggles to reconcile this fact with the ache of cosmic nostalgia that arises, from time to time, in the researcher’s heart: an intimation of vanished glory, of lost wholeness, a memory of the world unbroken. We call the moment at which this ache first arises “adolescence.” The feeling haunts people all their lives.