Theology not being my strong suit, I haven't read much St. Aquinas, but the fruit of his work was fantastic. Always a good sign. I like that he recommended the Church reduce Jewry to chattel slavery. He also wrote that masturbation is a graver sin than rape, because you're not using your body in a way which God intended it to be used. It shocked me at the time, being raised in a liberal feminist home, but it makes complete sense.