Moreover, the perilous power that I was renouncing was even more perilous than we suppose. Pities, dreams, do not fly away unaccompanied. When we alter thus the conditions in which we go to sleep, it is not our dreams alone that fade, but, for days on end, for years it may be, the faculty not merely of dreaming but of going to sleep. Sleep is divine but by no means stable; the slightest shock makes it volatile. A lover of habits, they retain it every night, being more fixed than itself, in the place set apart for it, they preserve it from all injury, but if we displace it, if it is no longer subordinated, it melts away like a vapour. It is like youth and love, never to be recaptured.