An enemy who sees the error of his ways ceases to be an enemy.

They sensed that what had happened around them and in their presence, and in them, was irrevocable. Never again could it be cleansed; it would prove that man, the human species - we, in short - had the potential to construct an enormity of pain, and that pain is the only force created from nothing, without cost and without effort. It is enough not to see, not to listen, not to act.

I am not even alive enough to know how to kill myself

If it is true that there is no greater sorrow than to remember a happy time in a state of misery, it is just as true that calling up a moment of anguish in a tranquil mood, seated quietly at one's desk, is a source of profound satisfaction.

To accuse another of having weak kidneys, lungs, or heart, is not a crime; on the contrary, saying he has a weak brain is a crime. To be considered stupid and to be told so is more painful than being called gluttonous, mendacious, violent, lascivious, lazy, cowardly: every weakness, every vice, has found its defenders, its rhetoric, its ennoblement and exaltation, but stupidity hasn't.

Perhaps Kafka laughed when he told stories [. . . ] because one isn't always equal to oneself.

Conquering matter is to understand it, and understanding matter is necessary to understanding the universe and ourselves: and that therefore Mendeleev's Periodic Table, which just during those weeks we were learning to unravel, was poetry.