In the mountains of truth, you never climb in vain.

In a hamlet of ten households, there are bound to be those who are my equal in doing their best for others and in being trustworthy in what they say, but they are unlikely to be as eager to learn as I am.

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.

The fervor about having the truth counts very little today in relation to that other fervor, more gentle and silent, to be sure, for seeking the truth, a search that does not tire of learning afresh and testing anew.

It is not when truth is dirty, but when it is shallow, that the lover of knowledge is reluctant to step into its waters.

I believe there exists, & I feel within me, an instinct for the truth, or knowledge or discovery, of something of the same nature as the instinct of virtue, & that our having such an instinct is reason enough for scientific researches without any practical results ever ensuing from them.