A man's heart is right when he wills what God wills.

It is necessary to posit something which is necessary of itself, and has no cause of its necessity outside of itself but is the cause of necessity in other things. And all people call this thing God.

A scrap of knowledge about sublime things is worth more than any amount about trivialities.

Man can sin against nature in two ways. First, when he sins against his specific rational nature, acting contrary to reason. In this sense, we can say that every sin is a sin against man's nature, because it is against man's right reason.

Perfection of moral virtue does not wholly take away the passions, but regulates them.

To pretend angels do not exist because they are invisible is to believe we never sleep because we don't see ourselves sleeping.

There must be must be a first mover existing above all – and this we call God.