So blind is the curiosity by which mortals are possessed, that they often conduct their minds along unexplored routes, having no reason to hope for success, but merely being willing to risk the experiment of finding whether the truth they seek lies there.

Each problem that I solved became a rule, which served afterwards to solve other problems.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

There is nothing so strange and so unbelievable that it has not been said by one philosopher or another.

The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, to the knowledge of which man is competent, are mutually connected in the same way, and that there is nothing so far removed from us as to be beyond our reach, or so hidden that we cannot discover it, provided only we abstain from accepting the false for the true, and always preserve in our thoughts the order necessary for the deduction of one truth from another.

The last rule was to make enumerations so complete, and reviews so comprehensive, that I should be certain of omitting nothing.

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

Of all things, good sense is the most fairly distributed: everyone thinks he is so well supplied with it that even those who are the hardest to satisfy in every other respect never desire more of it than they already have.