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

One cannot explain words without making incursions into the sciences themselves, as is evident from dictionaries; and, conversely, one cannot present a science without at the same time defining its terms.

I do not believe that a world without evil, preferable in order to ours, is possible; otherwise it would have been preferred. It is necessary to believe that the mixture of evil has produced the greatest possible good: otherwise the evil would not have been permitted. The combination of all the tendencies to the good has produced the best; but as there are goods that are incompatible together, this combination and this result can introduce the destruction of some good, and as a result some evil.

Nihil est sine ratione. There is nothing without a reason.

I hold that the mark of a genuine idea is that its possibility can be proved, either a priori by conceiving its cause or reason, or a posteriori when experience teaches us that it is in fact in nature.

He who understands Archimedes and Apollonius will admire less the achievements of the foremost men of later times.

To love is to be delighted by the happiness of someone, or to experience pleasure upon the happiness of another. I define this as true love.