vii-ix. Eloquence is natural, not in the perverted sense that the full exercise of speech is instinctive, but only to the extent that speech is the peculiar opportunity of mankind. x (837 B). “_Logica_, then, to show the widest meaning of the word, is the theory of speaking or of discoursing. Sometimes it is contracted to the extent of limiting the force of the word to theories of discourse. Whether, therefore, it teaches the ways of reasoning or offers a rule for all speech, they are evidently unwise who call it useless; for either [the narrower or the wider scope] is taught by most famous theory as necessary. The twofold meaning of the word comes from its origin in Greek; for there λόγος means now speech (sermo), now theory (ratio). But that its meaning may be extended most widely, let us assign to it at present the control of all speech, so that nowhere it may be proved useless, and so that in its more general sense it may appear as a whole very useful and necessary.” xi. The idea of any art is to further nature by theory. xii (839 C). “But since _artes_ are of many kinds, the first of all for a mind bent on wisdom are the _artes liberales_. All these are included in the theory either of the Trivium or of the Quadrivium; and so great efficacy they are said to have achieved among the ancients, who taught them assiduously, that they opened all reading, roused the mind to everything, and sufficed to resolve the difficulties of all questions which can be settled. They to whom the theory of the Trivium expounded the secrets of all speech, the law of the Quadrivium the secrets of all nature, needed no teachers to explain their books or resolve their questions.” xiii (840 A). “Of all these the first is _logica_, in that part of it which deals with the first teaching of speech.... This is _grammatica_, the lore of speaking and writing correctly, the origin of all liberal disciplines ... the cradle of all philosophy ... the first nurse of all literary study.” xiv-xvi. _Grammatica_ imitates nature by keeping congruity of thought.[21] For instance, it does not tolerate adjectives of secondary application with nouns of primary application.