Thus in Holy Writ no confusion results, for all the senses are founded on one—the literal—from which alone can any argument be drawn, and not from those intended in allegory, as Augustine says (Epis. 48). Nevertheless, nothing of Holy Scripture perishes on account of this, since nothing necessary to faith is contained under the spiritual sense which is not elsewhere put forward by the Scripture in its literal sense.
This comboxer uses this quotation in order to justify his rejection of a typological argument for the perpetual virginity of the Blessed Virgin—one that views her as the Ark of the new covenant and compares her to the Old Testament ark of the covenant.
There are at least two reasons why this use of St. Thomas for this purpose is improper. In the first place, since the New Testament itself makes use of typologies, it seems to be proving too much to say that they are invalid in and of themselves: if it is to be assumed that typologies are invalid, then we would forced to conclude that the New Testament writers had gone too far themselves in making use of them. I have heard Protestants say that the only valid types are the ones that Scripture uses and that all others are invalid, but we have no principled reason to accept this claim.
In the second place, the comboxer misquotes St. Thomas by omission, and consequently causes him to appear to accept something that he does not. Earlier in the same article, St. Thomas said this:
Since the literal sense is that which the author intends, and since the author of Holy Writ is God, Who by one act comprehends all things by His intellect, it is not unfitting, as Augustine says (Confess. xii), if, even according to the literal sense, one word in Holy Writ should have several senses. [Emphasis added]
So it’s clear that you can’t appeal to Aquinas as an authority for the idea that the literal sense of Scripture is something singular, which would rule out typology. This fact is made more clear from Aquinas’ own use of the Bible. A single example will suffice for now: his commentary on St. Gabriel’s salutation to the Blessed Virgin, which we looked at here. There are many examples of his use of Scripture in the commentary, but perhaps the most interesting for our purposes here is the following, from his argument in the commentary for the Virgin’s purity:
Third, she exceeds the angels in her purity, for the Blessed Virgin was not only pure in herself, but she also obtained purity for others. For she was most pure with respect to guilt, because neither mortal nor venial sin could be imputed to this virgin, and she was equally pure with respect to punishment.
Three curses come to men because of sin…The third is common to men and women, namely that into dust they shall return. The Blessed Virgin was free of this, because she was assumed in the body into heaven. For we believe that after death she was raised up and borne to heaven. Psalm 131:8: Arise, O “Lord, into thy resting place, thou and the ark of thy majesty.”
The most important thing to note here is that he specifically quotes Ps. 131:8 in such fashion as to refer to Mary as “the ark of thy majesty.” In other words, he’s making the exact same typological argument that our Protestant comboxer objected to, and the same argument that he erroneously claimed was invalid in the eyes of Aquinas. Hence we see that, quite contrary to what our comboxer asserts, Aquinas believed in the legitimacy of typologies like this, and actually made use of them himself.