Chess is the gymnasium of the mind.

You see, if the height of the mercury [barometer] column is less on the top of a mountain than at the foot of it (as I have many reasons for believing, although everyone who has so far written about it is of the contrary opinion), it follows that the weight of the air must be the sole cause of the phenomenon, and not that abhorrence of a vacuum, since it is obvious that at the foot of the mountain there is more air to have weight than at the summit, and we cannot possibly say that the air at the foot of the mountain has a greater aversion to empty space than at the top.

The weather and my mood have little connection. I have my foggy and my fine days within me; my prosperity or misfortune has little to do with the matter.

If it is an extraordinary blindness to live without investigating what we are, it is a terrible one to live an evil life, while believing in God

If men knew themselves, God would heal and pardon them.

Force rules the world-not opinion; but it is opinion that makes use of force.

As we speak of poetical beauty, so ought we to speak of mathematical beauty and medical beauty. But we do not do so; and that reason is that we know well what is the object of mathematics, and that it consists in proofs, and what is the object of medicine, and that it consists in healing. But we do not know in what grace consists, which is the object of poetry.