I hope that posterity will judge me kindly, not only as to the things which I have explained, but also to those which I have intentionally omitted so as to leave to others the pleasure of discovery.
Divide each difficulty into as many parts as is feasible and necessary to resolve it.
It is not enough to have a good mind; the main thing is to use it well.
To know what people really think, pay regard to what they do, rather than what they say.
I think therefore I exist.
Each problem that I solved became a rule, which served afterwards to solve other problems.
Perfect numbers like perfect men are very rare.
If you would be a real seeker after truth, you must at least once in your life doubt, as far as possible, all things.
The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.
Everybody thinks himself so well supplied with common sense that even those most difficult to please. . . never desire more of it than they already have.