Augustine says this in Book 1, chapter 2: “The purpose of all the Catholic commentators I have been able to read on the divine books of both testaments, who have written before me on the trinity which God is…”
The version I have is translated by Edmund Hill, who has a footnote here which I find extremely to the point: “It is worth noting that Augustine takes it for granted that to write on the Trinity was to interpret the Scriptures. There was no question of dogmatic writers and bible commentators belonging to different species.” I couldn’t agree more. It is a fun quote, is it not?
David Gadbois
greenbaggins
paigebritton
Reed Here
reformedmusings
rfwhite
Ron Henzel
Green Baggins 
Kymanika said,
December 28, 2006 at 7:35 pm
Yes, I like that. I wish I had the ability to word things like that. Hence, my appreciation of those teachers of the Church.