1. Most of Q.1 is devoted to figuring out what exactly it means to say that sacra doctrina is a science. Having established that the principles of sacra doctrina do not disqualify it from being a science, in the third article St. Thomas asks whether it counts as only one science or should be divided into several. This is of great interest to us today, given how fractured theology is in the academy, and how little exchange there is between people who do scripture, dogmatics, and morals (not to mention other, newer divisions).
2. The reason for this question is that, as we mentioned in the previous article, one of the qualifications for being a science is that a given body of knowledge concern a single type of object. Now, divine revelation speaks of many things: God, men, angels, and other creatures. Hence it seems that several sciences would flow from sacra doctrina—one for each of these kinds of things. Even if we were to divide them into the most generic classes, there remains a huge gap between God and creatures.
3. Furthermore, when we look at all the things discussed by sacra doctrina, including morality, the divine nature, anthropology, etc., and look at the parallel disciplines which emerge from philosophy, we see that they are divided into separate sciences, so it would only be reasonable to divide sacra doctrina into several sciences, each of which would treat one of these objects.
4. Against the impulse to divide theology, St. Thomas insists that sacra doctrina is one science, and that its principle object is God. He points out that what unifies a science isn't necessarily that it deals with only one kind of thing, but that it deals with different things under a single formality or aspect. Thus in studying color, one studies all sorts of colored objects, but under the aspect of their colored-ness. Likewise, sacra doctrina considers many different objects, all of which are united under the aspect of being supernaturally revealed by God.
5. Furthermore, St. Thomas points out that properly speaking sacra doctrina does have only one object, which is God, and treats of other things only insofar as they are related to him: either as proceeding from him in creation or returning to him in redemption.
Outline of Article
–Sacra doctrina deals with many different sorts of objects.
–The cases parallel to the different objects of sacra doctrina are given different sciences in the natural order.
–A science is one not necessarily by the unity of its object, but sometimes by a single formality under which many diverse objects are considered.
–Sacra doctrina treats of God principally, and of creatures only inasmuch as they are referred to God, as cause or end.
–Locally diverse things can be considered together under a higher, more common idea. E.g. the common sense unifies the senses of taste, touch, sight, etc. under one sensory awareness. Sacra doctrina considers diverse things together by referring them to a higher thing: God.