 In logic, Lefèvre therefore bestowed his greatest energies on the first pars proloquendi of logic. The notion of proloquium sometimes had, for him, its more basic sense of “introduction” (e.g., 1503a); but he also used the term in its more technical sense of an axiom or proper principle of demonstration. In the Posterior Analytics I, Lefèvre glossed Aristotle’s account of principles for a demonstration as dealing with proloquia (1503a: 189v; see also 187r). He thus emphasized the logica vetus precisely because he hoped to ground the certainty of knowledge in trustworthy starting points. In contrast, he believed that the logica modernorum or more rhetorical portions of the Organon such as the Topics—the part most properly called dialectic—encouraged sophistic debate, i.e., developing arguments out of uncertain premises. Aristotle considered dialectic to be merely “probable” in its reasoning; as Lefèvre put it, rather than finding certain knowledge (scientia), which deploys syllogisms and enthymemes, topical dialectic is useful for directing “opinions” by means of less certain techniques as well, such as induction and example (Libri logicorum, 1503a: 229v). Aristotle had said the subject of the Topics was “exercises, colloquies, and the disciplines according to philosophy”. For Lefèvre, this meant the Topics were more appropriate for entertainment: 