Nicene and Post-Nicene Fathers, Ser. II, Vol. III:
Life and Works of Rufinus with Jerome's Apology Against Rufinus.: The office of a commentator.

16. For instance, Chrysippus and Antipater occupy themselves with thorny questions: Demosthenes and Æschines speak with the voice of thunder against each other; Lysias and Isocrates have an easy and pleasing style. There is a wonderful difference in these writers, though each of them is perfect in his own line. Again: read the book of Tully To Herennius; read his Rhetoricians; or, since he tells us that these books fell from his hands in a merely inchoate and unfinished condition, look through his three books On the orator, in which he introduces a discussion between Crassus and Antony, the most eloquent orators of that day; and a fourth book called The Orator p. 491 which he wrote to Brutus when already an old man; and you will realize that History, Oratory, Dialogue, Epistolary writing, and Commentaries, have, each of them, their special style. We have to do now with Commentaries. In those which I wrote upon the Ephesians I only followed Origen and Didymus and Apollinarius, (whose doctrines are very different one from another) so far as was consistent with the sincerity of my faith: for what is the function of a Commentary? It is to interpret another man’s words, to put into plain language what he has expressed obscurely. Consequently, it enumerates the opinions of many persons, and says, Some interpret the passage in this sense, some in that; the one try to support their opinion and understanding of it by such and such evidence or reasons: so that the wise reader, after reading these different explanations, and having many brought before his mind for acceptance or rejection, may judge which is the truest, and, like a good banker, may reject the money of spurious mintage. Is the commentator to be held responsible for all these different interpretations, and all these mutually contradicting opinions because he puts down the expositions given by many in the single work on which he is commenting? I suppose that when you were a boy you read the commentaries of Asper upon Virgil and Sallust, those of Vulcatius upon Cicero’s Orations, of Victorinus upon his Dialogues and upon the Comedies of Terence, and also those of my master Donatus on Virgil, and of others on other writers such as Plautus, Lucretius, Flaccus, Persius and Lucan. Will you find fault with those who have commented on these writers because they have not held to a single explanation, but enumerate their own views and those of others on the same passage?