Now we consider the distinction of corporeal and spiritual creatures: firstly, the purely spiritual creature which in Holy Scripture is called angel; secondly, the creature wholly corporeal; thirdly, the composite creature, corporeal and spiritual, which is man.

Concerning the angels, we consider first what belongs to their substance; secondly, what belongs to their intellect; thirdly, what belongs to their will; fourthly, what belongs to their creation.

Their substance we consider absolutely and in relation to corporeal things.

Concerning their substance absolutely considered, there are five points of inquiry:

A[1] Whether there is any entirely spiritual creature, altogether incorporeal?

A[2] Supposing that an angel is such, we ask whether it is composed of matter and form?

A[3] We ask concerning their number.

A[4] Of their difference from each other.

A[5] Of their immortality or incorruptibility.