I am convinced that the unwritten knowledge scattered among men of different callings surpasses in quantity and in importance anything we find in books, and that the greater part of our wealth has yet to be recorded.

The words 'Here you can find perfect peace' can be written only over the gates of a cemetery.

There is no way in which a simple substance could begin in the course of nature, since it cannot be formed by means of compounding.

It is unworthy of excellent men to lose hours like slaves in the labor of calculation which could be relegated to anyone else if machines were used.

Men act like brutes in so far as the sequences of their perceptions arise through the principle of memory only, like those empirical physicians who have mere practice without theory.

Now where there are no parts, there neither extension, nor shape, nor divisibility is possible. And these monads are the true atoms of nature and, in a word, the elements of things.

There is nothing waste, nothing sterile, nothing dead in the universe; no chaos, no confusions, save in appearance.