Nor were the large philosophy of rhetoric in Cicero’s _De oratore_, the great survey of Quintilian, the later medieval guides. The prevalent textbooks were Cicero’s youthful digest _De inventione_ and a second book universally attributed to him, the _Rhetorica ad Herennium_. Though the survival of these minor works may be due partly to the accidents of manuscripts, their persistence has other causes. _De inventione_ reduces to summary what the middle age taught least, those counsels of preparation and ordering which ancient teaching had progressively adjusted to oral discourse, and for which the earlier middle age had less opportunity. The _Rhetorica ad Herennium_, comparatively summary also as to analysis and sequence, is devoted largely to style, and reduces stylistic ornament to a list so conveniently specific that medieval schools made it a ritual. Though the greater Cicero and Quintilian were known to such original minds as Gerbert in the tenth century and John of Salisbury in the twelfth, they were hardly available for the usual course of teaching. Medieval rhetoric was generally a lore of style. Here _rhetorica_ tended to coincide with that school study of Latin poetry which was a recognized function of _grammatica_. The constant quotation of Horace’s “Ars poetica” is one of the signs of the merging of poetic with rhetoric. The conventional doctrine from both was largely of descriptive dilation. Among the effects of this teaching which outlast schooling and reach beyond Latin are certain conventions of vernacular poetry. Conversely, poetic advance in the vernaculars is seen in breaking away not only from school rhetoric, but from rhetoric altogether. The main medieval fields proper to rhetoric were sermons and letters. The former, exploring their rhetoric in the earlier centuries, continued to feel the example, perhaps more than the precept, of St. Augustine. Even the Dominicans had no need to seek a new lore of oral composition. What is distinctive in sermon composition of the twelfth century is oftener poetic than rhetoric. Letters, on the other hand, are at once a legitimate application of ancient rhetoric and a distinctively medieval development. They practically comprehend the medieval rhetoric of written prose. Though ordinary routine was largely content, as in any other time, with correctness, and therefore with recipe and formulary, serious study of both composition and style is evident in the better manuals, and conspicuous in those achievements which are part of medieval literature.