In a question about Augustine, this quotation is given:
Frustra itaque nonnulli, immo quam plurimi, aeternam damnatorum poenam et cruciatus sine intermissione perpetuos humano miserantur affectu, atque ita futurum esse non credunt
— Augustine, Enchiridion, §112,
It is quite in vain, then, that some—indeed very many—yield to merely human feelings and deplore the notion of the eternal punishment of the damned and their interminable and perpetual misery. They do not believe that such things will be. (translation source)
This use of quam as a mere intensifier ("very") of a superlative surprised me. Perhaps I have seen it before, but I do not recall doing so. Is this normal in (classical) Latin?
To be clear, I am not inquiring about quam + superlative as used in e.g. "as many as possible" or "as many as I could find", both of which are common enough, nor about using it as an intensifier with a positive (which is possible though probably uncommon).
I could not find a description of this use in Lewis & Short.