"It is evident that one cannot say anything demonstrable about the problem before having resolved these preliminary questions, and yet we hardly possess the necessary information to solve some of them."

“The works which this man leaves behind him occupy a few pages only; their importance is not greatly superior to their extent.”

“To spread healthy ideas among even the lowest classes of people, to remove men from the influence of prejudice and passion, to make reason the arbiter and supreme guide of public opinion; that is the essential goal of the sciences; that is how science will contribute to the advancement of civilization, and that is what deserves protection of governments who want to insure the stability of their power.”

“The natural food of man, judging from his structure, appears to consist of the fruits, roots, and other succulent parts of vegetables.”

“Why has not anyone seen that fossils alone gave birth to a theory about the formation of the earth, that without them, no one would have ever dreamed that there were successive epochs in the formation of the globe.”