Why is Aquinas difficult to understand? It is certainly not because his writing is obscure. In contrast to many famous philosophers, Aquinas is a remarkably clear and concise writer. Unlike St. Augustine (354–430), Aquinas is not an accomplished literary stylist; unlike Duns Scotus (1265/66–1308), he does not pursue metaphysical subtleties to the vanishing point. Nor does his vocabulary pose any special problems. Apart from some technical terms that we will introduce along the way, Aquinas deals