You should read St. Thomas Aquinas both for the subject matter and because of the way he teaches. Theology is worth it, but he's also an example of how to teach anyone anything.

Diving in to the Summa

He says in the prologue to the Summa Theologiae that he's going to present theology to beginners, in a way that is appropriate for beginners. So you always have to remember the table of contents. In fact, whenever you read a book, especially one constructed by a genius, realize that it has been planned out carefully. The table of contents gives you the blueprint to the thought.

So Thomas divides the book up into questions and articles. The Questions are the big topics, and the articles are the aspects of the question. He also gives you the objections first, so that you know what is at stake.

Question 1 Article 1

Question 1 of the whole book: the nature and extent of sacred doctrine. In other words, what is this thing we are studying? A good physics textbook starts with the definition of physics. I have a baking textbook that starts with a definition of bread. This is good pedagogy.

Article 1: Whether besides philosophy, any further doctrine is needed. In other words, do we need this 'theology' thing at all? I used to start my ethics classes with a question on relativism--are moral norms real in some way, or are they entirely dependent on the choice of the individual? If so, there was no need to meet for the rest of the semester!

St Thomas always starts with the contrary position: it seems that we don't need anything else than philosophy, and he gives two reasons:

• You shouldn't seek that which is above reason. Stick with philosophy!

• Philosophy speaks of God anyway--see Aristotle, so there's no need for anything else.

I can imagine a younger Karl using these arguments with one of the Dominican sisters to try to get out of class.

Before Thomas gets to the main argument, he'll give an "On the contrary", which is usually an appeal to some authority. In this case it's 2 Tim 3:16 about scripture being inspired by God and useful for teaching. Such inspired scripture isn't covered by philosophy, and therefore we need a science of scripture, namely sacred doctrine/theology.

You might think that this is all religious people need. After all, they have faith, which has nothing to do with reason! But St. Thomas disagrees. There is one Truth, and both reason and faith get you there. If the Bible is accepted because of faith, and faith comes from the Bible, how would you ever convince anyone who didn't already agree with you? Thomas uses reason to get as far as possible, proving what can be proved and removing objections to what cannot be proved.

This is why he doesn't stop with the appeal to authority. There's an "I answer that" section where he uses arguments accessible to all. There are two arguments:

1. The telos or end of the human being goes beyond that which reason can grasp. This is a state of affairs accessible to anyone who thinks deeply about human nature. We are such that we tend never to be satisfied with anything, for long. If you got the whole world, would you be satisfied? Not for long! Therefore, any goal which satisfies will be beyond the whole world, and you wouldn't know about that goal unless it was revealed to you.

2. Even if philosophy can get to lots of true things about God, philosophy is difficult. "The truth about God such as reason could discover, would only be known by a few, and that after a long time, and with the admixture of many errors." If salvation depends on knowledge of the Truth, there needs to be a way for most people, who aren't smart enough to do philosophy, to get that knowledge. Thus it's a good thing to have revelation/theology.

Note that these arguments start from truths accessible to you. Reflect on the finitude of human nature. Read the existentialists. Sit in your office at 3pm on a Tuesday and consider the apparent meaningless of life. There must be something more, right? Thus #1 above. Now think about your fellow humans and how often they think deeply about anything. Not too often, right? If reaching our proper end depended solely on our own powers of thinking, we'd be doomed. Thus #2 above.

This is not bible-thumping. St. Thomas respects your reason and appeals to it. Think along with him and see if you agree!

What about the objections?

• The first objection said we shouldn't seek things beyond reason, but if there has been any divine revelation, it changes the equation. If God speaks to man, we ought to listen.

• The second objection said that God is already treated of in philosophy, and so we don't need another science. Thomas says that different sciences can talk about the same things. Both astronomers and physicists talk about the roundness of the earth, after all, but in different ways. Sciences overlap in their subjects, even if they differ in their method.

Thomas is a good teacher

So, right at the beginning of his enormous theology book for beginners, he's established that there needs to be such a thing as theology, and you've got an idea of how he's going to proceed, always respecting the opinions of those who disagree, presenting the relevant authorities, and appealing to your powers of reason.

Beyond his value as a teacher of a particular subject is his value as an exemplar of a teacher. Don't you wish that other people would teach this way?