We proceed to the second article thus:

1. It seems that sacred doctrine is not a science. For every science depends on principles which are self-evident, whereas sacred doctrine depends on articles of faith which are not self-evident, since they are not conceded by everybody. As is said in II Thess.3:2: "all men have not faith." Hence sacred doctrine is not a science.

2. Again, there is no science of particulars. [4] But sacred doctrine is concerned with particulars, such as the deeds of Abraham, Isaac, Jacob, and others. It is not therefore a science.

On the other hand: Augustine says (14 De Trin.1): "by this science only is faith begun, nourished, defended, and strengthened." Now this is true of no science except sacred doctrine. Sacred doctrine is therefore a science.

I answer: sacred doctrine is a science. But we must realize that there are two kinds of sciences. Some of them, such as arithmetic, geometry, and the like, depend on principles known by the natural light of reason. Others depend on principles known through a higher science. Thus the science of perspective depends on principles known through geometry, and music on principles known through arithmetic. Sacred doctrine is a science of the latter kind, depending on principles known through a higher science, namely the science of God and the blessed. Just as music accepts the principles given to it by arithmetic, so does sacred doctrine accept the principles revealed to it by God.

On the first point: the principles of any science are either self-evident, or derived from what is known through a higher science. The principles of sacred doctrine are so derived, as we have said.

On the second point: sacred doctrine does not narrate particular things because it is principally concerned with them. It introduces them as examples to follow, as do the moral sciences; and also as proofs of the authority of those through whom the divine revelation, on which sacred Scripture and sacred doctrine are founded, reaches us.

[4] Aristotle held that the sheer individuality of a particular, its "primary substance," could never be an object of science because it could never be a predicate. Only the "secondary substance," or essence, comprising the universals which must apply to a particular of a certain kind, could be known scientifically. Cf. Categories V.