"Now the Lord is that Spirit: and where the spirit of the Lord is, there is liberty." -- 2 Corinthians 3:17
Your loss.
I don't much about his Summa, have read that Aquinas influenced Calvin's thought, and from the excercpts I've read I can see some similarity. Forceful departure comes with the synthesis of grace and nature, that I think Aquinas upheld and Calvin rejected. Trent's conclusion, paraphrased here, that it's 100% God and 100% man, leaves an equation that is not a real equation. I don't think it's a workable thing. Though I do think that it's as Lewis says it is: The real inter-relation between God's omnipotence and Man's freedom is something we can't find out.
The thing that rings so confusing about Aquinas to me, is on the one hand his trepidation about language and its efficacy in how we approach God, and on the other, his advance of transubstantiation, later to become an article of faith. How is that one travels from such opposite vistas to impact the faith of Christ and His Apostles in the way that he did?
My ex-confessor and ex-priest was a smart man and a holy man, I think. I'm quite sure he was true to his celibacy vows, because he was very, very grouchy, all the time.
All kidding aside though, one day as I was thinkng about all of this, it dawned on me that his Catholicism was not one that he owned. And by owning I mean, having the capacity to believe that there was a possiblity what he believed might be wrong. When that's the case you start to build belief in your doctrine from the bottom up, and when you do that you have an understanding of what it is that you believe that you can make plain to any person who would make an inquiry. Had he truly owned his Catholicism he would have been able in plain words to address my questions, without referring me to Aquians. Even if a segment of his explanation involved the phrase "it's something I take on faith, and you must too." To me, it showed a marked misunderstanding of things, chief of which is the role of a pastor.