Nothing can be said: nothing sure, nothing probable, nothing honest. Better to err through omission than through commission: better to refrain from steering the fate of others, since it is already so difficult to navigate one's own.

If you and your child were going to be killed tomorrow, would you not give him to eat today?

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

Monsters exist, but they are too few in numbers to be truly dangerous. More dangerous are…the functionaries ready to believe and act without asking questions.

We must be listened to: above and beyond our personal experience, we have collectively witnessed a fundamental unexpected event, fundamental precisely because unexpected, not foreseen by anyone. It happened, therefore it can happen again: this is the core of what we have to say. It can happen, and it can happen everywhere.

In history and in life one sometimes seems to glimpse a ferocious law which states: to he that has, will be given; from he that has not, will be taken away.

A scientist's life, the author says, is indeed conflictual, formed by battles, defeats, and victories: but the adversary is always and only the unknown, the problem to be solved, the mystery to be clarified. It is never a matter of civil war; even though of different opinions, or of different political leanings, scientists dispute each other, they compete, but they do not battle: they are bound together by a strong alliance, by the common faith "in the validity of Maxwell's or Boltzmann's equations," and by the common acceptance of Darwinism and the molecular structure of DNA.