I did not imitate the skeptics who doubt only for doubting's sake, and pretend to be always undecided; on the contrary, my whole intention was to arrive at a certainty, and to dig away the drift and the sand until I reached the rock or the clay beneath.

When writing about transcendental issues, be transcendentally clear.

Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.

Travelling is almost like talking with those of other centuries.

A state is better governed which has few laws, and those laws strictly observed.

These long chains of perfectly simple and easy reasonings by means of which geometers are accustomed to carry out their most difficult demonstrations had led me to fancy that everything that can fall under human knowledge forms a similar sequence; and that so long as we avoid accepting as true what is not so, and always preserve the right order of deduction of one thing from another, there can be nothing too remote to be reached in the end, or to well hidden to be discovered.

Nothing comes out of nothing.