It is possible to demonstrate God's existence, although not a priori, yet a posteriori from some work of His more surely known to us.

Now it seems that everything in the world stems from sources other than God, since the products of nature have their source in nature; deliberate effects can be traced back to human reason or will as their source. There is no need then to assume that God exists.

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.

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.

God should not be called an individual substance, since the principle of individuation is matter.

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

If a thing can be done adequately by means of one, it is superfluous to do it by means of several; for we observe that nature does not employ two instruments [if] one suffices.