Event Causation, Substance Causation, and Aquinas' Cosmological Arguments

I wonder if one might spell out the difference between Aquinas' first and second ways in terms of the distinction between event causation and substance causation. The idea would be something like this: in the first way, we are taking the aggregate of all the contingent events (or perhaps all of the changes) that there are, and asking what causally accounts for this aggregate. In the second way, we are taking the aggregate of all the contingent substances that there are, and asking what causally accounts for this aggregate.

This aggregation-based reading of the Five Ways is inspired by Geach (1961), Lamont (1995), and Martin (1997), among others. While I doubt that this is what the historical Aquinas had in mind, I think it makes for a better argument than do other (perhaps more textually faithful) interpretations of the Five Ways.