some would add that which deals with definitions and another part concerning canons or criteria : some, however, dispense with the part about definitions. Now the part which deals with canons or criteria they admit as a means for the discovery of truth, since in the course of it they explain the different kinds of perceptions that we have. And similarly the part about definitions is accepted as a means of recognizing truth, inasmuch as things are apprehended by means of general notions. Further, by rhetoric they understand the science of speaking well on matters set forth by plain narrative, and by dialectic that of correctly discussing subjects by question and answer ; hence their alternative definition of it as the science of statements true, false, and neither true nor false. Rhetoric itself, they say, has three divisions : deliberative, forensic, and panegyric. Rhetoric according to them may be divided into invention of arguments, their expression in words, their arrangement, and delivery ; and a rhetorical speech into introduction, narrative, replies to opponents, and peroration. Dialectic (they hold) falls under two heads : subjects of discourse and language. And the subjects fall under the following headings : presentations ° and the various products to which they give rise, propositions enunciated and their constituent subjects and predicates, and similar terms whether direct or reversed, genera and species, arguments " simple ideas," for which Hume substituted " impressions and ideas " ; but this is hardly so ; for (pavraaiai are " given " as it were from without, and then with them as materials the mind itself constructs general notions and concepts.