Aquinus? Maybe he did formulate one use of the term... but the primary source of our basic way of defining causality was from Aristotle.... http://en.wikipedia.org/wiki/Causality#Aristotelian

I sat thru some LONG classes on the various conceptual types of causes many years ago. They were logically quite complete when discussing events within existing reality, but nothing about the system quite copes with **ultimate** causality.