The soul is perfected by knowledge and virtue.

Eternity is called whole, not because it has parts, but because it is lacking in nothing.

There is nothing in your mind which wasn't experienced before hand.

If... the motion of the earth were circular, it would be violent and contrary to nature, and could not be eternal, since ... nothing violent is eternal .... It follows, therefore, that the earth is not moved with a circular motion.

Good can exist without evil, whereas evil cannot exist without good.

We can't have full knowledge all at once. We must start by believing; then afterwards we may be led on to master the evidence for ourselves.

Wonder was the motive that led people to philosophy ... wonder is a kind of desire in knowledge. It is the cause of delight because it carries with it the hope of discovery.