Nothing is more important than to see the sources of invention which are, in my opinion more interesting than the inventions themselves.

There is a certain destiny of everything, regulated by the foreknowledge and providence of God in His works.

Nothing is necessitated whose opposite is possible.

I also readily admit that there are animals, taken in the ordinary sense, that are incomparably larger than those we know of, and I have sometimes said in jest that there might be a system like ours which is the pocketwatch of some enormous giant.

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.

The knowledge which we have acquired ought not to resemble a great shop without order, and without an inventory; we ought to know what we possess, and be able to make it serve us in need.

Every mind has a horizon in respect to its present intellectual capacity but not in respect to its future intellectual capacity.