"On day ten, I turned a corner� I felt awful, as usual, in the morning, but a completely different person in the afternoon."

"This was delightful, and wholly unexpected: there was no intimation, beforehand, that such a transformation was about to happen," writes Oliver Sacks, describing the aftermath of treatment for metastatic liver cancer.

How much of this was a reestablishment of balance in the body; how much an autonomic rebound after a profound autonomic depression; how much other physiological factors; and how much the sheer joy of writing, I do not know. But my transformed state and feeling were, I suspect, very close to what Nietzsche experienced after a period of illness and expressed so lyrically in The Gay Science:

Gratitude pours forth continually, as if the unexpected had just happened � the gratitude of a convalescent � for convalescence was unexpected�. The rejoicing of strength that is returning, of a reawakened faith in a tomorrow and the day after tomorrow, of a sudden sense and anticipation of a future, of impending adventures, of seas that are open again.