The errors of great men are venerable because they are more fruitful than the truths of little men.

Belief in the truth commences with the doubting of all those truths we once believed.

There is no pre-established harmony between the furtherance of truth and the well-being of mankind.

This truth may be unfashionable, unpalatable, no doubt unpopular, but, if it is the truth, the story of mankind shows that war was universal and unceasing for millions of years before armaments were invented or armies organized. Indeed, the lucid intervals of peace and order only occurred in human history after armaments in the hands of strong governments have come into being, and civilization in every age has been nursed only in cradles guarded by superior weapons and superior discipline.

Here the ways of men part: if you wish to strive for peace of soul and pleasure, then believe; if you wish to be a devotee of truth, then inquire.

We have no organ at all for knowledge, for truth: we know (or believe or imagine) precisely as much as may be useful in the interest of the human herd, the species: and even what is here called usefulness is in the end only a belief, something imagined and perhaps precisely that most fatal piece of stupidity by which we shall one day perish.