Science is practical philosophy.

I have concluded the evident existence of God, and that my existence depends entirely on God in all the moments of my life, that I do not think that the human spirit may know anything with greater evidence and certitude.

Even the mind depends so much on temperament and the disposition of one's bodily organs that, if it is possible to find a way to make people generally more wise and more skilful than they have been in the past, I believe that we should look for it in medicine. It is true that medicine as it is currently practiced contains little of much use.

Travelling is almost like talking with those of other centuries.

And as it is the most generous souls who have most gratitude, it is those who have most pride, and who are most base and infirm, who most allow themselves to be carried away by anger and hatred.

Common sense is the most fairly distributed thing in the world, for each one thinks he is so well-endowed with it that even those who are hardest to satisfy in all other matters are not in the habit of desiring more of it than they already have.

With me, everything turns into mathematics.