First, it includes the whole basis of science or theory on which the Art rests: it is a Philosophy of Rhetoric, expounded by a theorist--rather than an Art of Rhetoric, taught to learners by a master. To teach the observance of certain rules or precepts is one thing: to set forth the reasons upon which those rules are founded, is another--highly important indeed, and proper to be known by the teacher; yet not necessarily communicated, or even communicable, to all learners. Quintilian, in his Institutio Rhetorica, gives both:--an ample theory, as well as an ample development of rules, of his professional teaching. But he would not have thought himself obliged to give this ample theory to all learners. With many, he would have been satisfied to make them understand the rules, and to exercise them in the ready observance thereof. [Side-note: Plato includes in his conception of Art, the application thereof to new particular cases.--This can never be taught by rule.] Secondly, Plato, in defining the Art of Rhetoric, includes not only its foundation of science (which, though intimately connected with it, ought not to be considered as a constituent part), but also the application of it to particular cases; which application lies beyond the province both of science and of art, and cannot be reduced to any rule. "The Rhetor" (says Plato) "must teach his pupils, not merely to observe the rules whereby persuasion is operated, but also to know the particular persons to whom those rules are to be applied--on what occasions--within what limits--at what peculiar moments, &c.[114] Unless the Rhetor can teach thus much, his pretended art is no art at all: all his other teaching is of no value." Now this is an amount of exigence which can never be realised. Neither art nor science can communicate that which Plato here requires. The rules of art, together with many different hypothetical applications thereof, may be learnt: when the scientific explanation of the rules is superadded, the learner will be assisted farther towards fresh applications: but after both these have been learnt, the new cases which will arise can never be specially foreseen. The proper way of applying the general precepts to each case must be suggested by conjecture adapted to the circumstances, under the corrections of past experience.[115] It is inconsistent in Plato, after affirming that nothing deserves the name of art[116] except what is general--capable of being rationally anticipated and prescribed beforehand--then to include in art the special treatment required for the multiplicity of particular cases; the analogy of the medical art, which he here instructively invokes, would be against him on this point. [Footnote 114: Plato, Phædr. pp. 268 B, 272 A.]