Long before he wrote the Summa, St. Thomas treated of the question “whether the first truth is the object of faith” in his commentary on Peter Lombard’s Sentences, (Bk. 3, Distinction 24, Question 3, Article 1). Each of the objections and the sed contra of his Summa article is parallel in content to an objection or sed contra in the Sentences commentary. The parallels are not so verbally close as to suggest that St. Thomas had the text of his Sentences commentary in front of him while he wrote the Summa article, but strong enough to argue that he was somewhat consistent over time in how he dealt with the question.
In my last post, I pointed out that St. Thomas illustrates the formal/material object distinction with geometry when he is talking about faith and with sight when he is talking about Sacred Doctrine. As I noted, this is surprising: since geometry is a science, one would expect him to use that as an example for Sacred Doctrine, which he also argues is a science; and since Scripture uses sight as a metaphor for faith, one would expect the sight metaphor to come up in connection with faith.
The unexpected switch is all the more interesting because St. Thomas uses the sight example to illustrate the formal/material object distinction when he deals with faith in the Sentences commentary. In other words, in his earlier work he did what one would expect; in his later work, despite using some of the same objections and the same quotation in the sed contra, he changed the example he uses from sight to geometry. I wish I knew what he had in mind!