Having read through one hundred and twelve of the topics in Peter Kreeft’s Practical Theology: Spiritual Direction from St. Thomas Aquinas, an accurate enough opinion of it has formed in my mind. The book–as anything written on St. Thomas’s theology–is quite dense, so I abandoned my hope of reading through its 366 pages in a month. I cannot help but admire how Kreeft either draws passages from the Summa Theologica easily applicable to everyday life or shows the relevance of more esoteric theology to living a good life. The prose and philosophy are both clear and direct, as may be expected from a Thomist. Besides St. Thomas, Kreeft quotes a wide variety of other Christian thinkers on these topics, especially C. S. Lewis, G. K. Chesterton, and George MacDonald. He also seems most at home with the ancient philosophers Plato and Aristotle.
Though, in regard to Plato, Kreeft often harps on a fallacy in Platonic philosophy: the idea that sin is only caused by ignorance. Plato believed that if ignorance were removed from a human being completely, he would not sin. We even see this idea a little in medieval philosophy when St. Bonaventure writes that Christ was like us in everything “except sin and ignorance” (See St. Bonaventure’s Tree of Life). However, Kreeft remarks that people sin despite knowing that it will make them miserable. Ignorance of goodness is not the only cause of sin. As Kreeft points out, we are all a little insane in cleaving to those things which cause us misery. Eliminating ignorance by doing things like reading philosophy and theology only goes so far: we need grace and the practice of virtue.
Medieval Otaku 