It is impossible for wisdom to be taught save through words. But words are not sufficient to teach unless they be pithy, and a man cannot speak pithily, unless his discussion be eloquent, supported by evidence, and convincing, that is, unless he has words (1) capable of speaking about everything, (2) able to be apprehended or known, and (3) to which one's mood can be inclined. Moreover he appropriately expresses what he says through literary art, rationally investigates through the discipline of logic, and effectively persuades through rhetoric. That in which Solomon was adept, therefore, is a part of philosophy; i.e., the science of discourse, which is threefold (as is clear).
Bonaventure, Collations on the Seven Gifts of the Spirit, Collation IV.
My translation above is somewhat crude and rather loose, by the way. One of the reasons is that English doesn't really have the words (or, perhaps: I don't really have the English words) to express in a straightforward way what Bonaventure is trying to say. The Latin, for those interested:
Impossibile est, quod sapientia fiat doctrina nisi per sermonem. Sermo autem non est sufficiens ad docendum, nisi sit sententiosus. Et non loquitur homo sententiose, nisi sit sermo eius discussivus, inquisitivus et persuasivus, scilicet quod habeat sermonem potentem ad loquendum omne illud, quod potest apprehendi vel nosci, vel ad quod affectus potest inclinari. Congrue autem exprimit quod dicit per grammaticam, rationabiliter investigat per scientiam logicam et efficaciter persuadet per rhetoricam. Ista est igitur pars philosophiae, scilicet scientia sermocinalis, quae triplex est, ut patet, quam adeptus est Salomon.
The occasion for this passage is Bonaventure's discussion of Solomon as an example of someone with the spiritual gift of knowledge. He argues that Solomon had the three types of knowledge (of words, of things, and of morals), each with their three divisions. The whole scheme is roughly as follows:
Sermocinalis (knowledge of discourse)
Grammatics (the literary art): how to speak, write, and interpret
Logic: how to reason and come to know
Rhetoric: how to persuade and influence
Veritatis Rerum (knowledge of things)
Physics: Concrete forms
Metaphysics: Abstract forms
Mathematics: Separate forms
De Morali (knowledge of morals)
Monastic (i.e., individual): pertaining to the organization of one's own life
Economic (i.e., domestic): pertaining to the organization of the family
Political: pertaining to the organization of the city
'Grammatica' is a much broader term than our 'grammar'; writing a history, for instance, would be an application of grammar in the medieval sense. It's the knowledge relevant to literary matters. (Usually considered to be practical, but there were exceptions to this.)