The Summa Theologica was a great philosophical work and really the pinnacle of medieval philosophy and theology. I've been reading it for a while now, (not without some difficulty) and I've come across what seems to be a contradiction. I would like to solve this by saying that I simply don't know the meaning of the word, "principle" or that the word Being is being used equivocally, but perhaps someone else in the ether of the net could help me with this problem:
According to Aquinas, Being is not a genus. But he also said that,"If God were in any Genus, He would be in the Genus 'being'". So the problems here are ones of confusion and contradiction. The confusion is from saying that Genus is not Being and yet, implying that Genus is being. The contradiction is that if Aquinas said that No Being is Genus, and that God would be Being, then it follows that God is in no Genus and therefore, God is not the principle of any Genus. So if that is true, doesn't that mean that since all causes are principles, that God is simply not a cause of things -by simple Modus Tollens? Later on, Aquinas also wrote that God was the principle of All being. If that's the case then by Universal Instantiation, shouldn't God be the principle of some Genus? Again am I simply using the word principle wrong?
This is all in Question 3, Article 5 of the Summa -"Whether God is Contained in a Genus?".