Context: Augustine’s Confessions are in form a prayer to God. In this passage, he expresses his conviction that he lacked a proper philosophical understanding in his early career, before he embraced Christianity. He recalls here an early essay he wrote on “the beautiful” and “the fitting”.
4.15.24
sed tantae rei cardinem in arte tua nondum videbam, omnipotens, qui facis mirabilia solus, et ibat animus per formas corporeas et pulchrum, quod per se ipsum, aptum autem, quod ad aliquid adcommodatum deceret, definiebam et distinguebam et exemplis corporeis adstruebam.
Translation: But I did not understand the principal point of so large a subject, Almighty, the one who made marvelous things all by yourself, and [my] mind was considering physical bodies; the Beautiful ones are admired for what they possess in themselves, while the Fitting ones are admired for how well they are adapted to other things. I was defining and distinguishing [the Beautiful and the Good] and filling out my account with examples of such physical things.
For quite a while, I was stalled by the lack of agreement between pulchrum, aptum, and formas. Finally, I decided to translate pulchrum as “Beautiful ones” and aptum as “Fitting ones”.
Is this a common pattern, the use of a neuter single adjective substantively, to denote an abstraction?