Just as eating against one's will is injurious to health, so studying without a liking for it spoils the memory, and it retains nothing it takes in.

Nature never breaks her own laws.

Strive to preserve your health; and in this you will better succeed in proportion as you keep clear of the physicians, for their drugs are a kind of alchemy concerning which there are no fewer books than there are medicines.

The lover is moved by the thing loved, as the sense is by that which perceives, and it unites with it and they become one and the same thing... when the lover is united with the beloved it finds rest there; when the burden is laid down there it finds rest.

I'm not contented to capture the world. I want to change it.

No human investigation can claim to be scientific if it doesn't pass the test of mathematical proof.

Every now and then go away, have a little relaxation, for when you come back to your work your judgment will be surer. Go some distance away because then the work appears smaller and more of it can be taken in at a glance and a lack of harmony and proportion is more readily seen.