The high-minded man must care more for the truth than for what people think.

For even they who compose treatises of medicine or natural philosophy in verse are denominated Poets: yet Homer and Empedocles have nothing in common except their metre; the former, therefore, justly merits the name of the Poet; while the other should rather be called a Physiologist than a Poet.

No one loves the man whom he fears.

But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.

We, on the other hand, must take for granted that the things that exist by nature are, either all or some of them, in motion.

Virtue is the golden mean between two vices, the one of excess and the other of deficiency.

It is evidently equally foolish to accept probable reasoning from a mathematician and to demand from a rhetorician demonstrative proofs.