The Rhetor--being assumed as already knowing the truth--if he wishes to make persuasion an art, must proceed in the following manner:--He must distribute the multiplicity of individual minds into distinct classes, each marked by its characteristic features of differences, emotional and intellectual. He must also distribute the manifold modes of discourse into distinct classes, each marked in like manner. Each of these modes of discourse is well adapted to persuade some classes of mind--badly adapted to persuade other classes: for such adaptation or non-adaptation there exists a rational necessity,[104] which the Rhetor must examine and ascertain, informing himself which modes of discourse are adapted to each different class of mind. Having mastered this general question, he must, whenever he is about to speak, be able to distinguish, by rapid perception,[105] to which class of minds the hearer or hearers whom he is addressing belong: and accordingly, which mode of discourse is adapted to their particular case. Moreover, he must also seize, in the case before him, the seasonable moment and the appropriate limit, for the use of each mode of discourse. Unless the Rhetor is capable of fulfilling all these exigencies, without failing in any one point, his Rhetoric is not entitled to be called an Art. He requires, in order to be an artist in persuading the mind, as great an assemblage of varied capacities as Hippokrates declares to be necessary for a physician, the artist for curing or preserving the body.[106] [Footnote 104: Plato, Phædrus, pp. 270 E, 271 A-D. [Greek: Tri/ton de\ dê\ diataxa/menos ta\ lo/gôn te kai\ psuchê=s ge/nê, kai\ ta\ tou/tôn pathê/mata, di/eisi ta\s ai)ti/as, prosarmo/ttôn e(/kaston e(ka/stô|, kai\ dida/skôn oi(/a ou)=sa u(ph' oi(/ôn lo/gôn di' ê(\n ai)ti/an e)x a)na/gkês ê( me\n pei/thetai, ê( de\ a)peithei=.]] [Footnote 105: Plato, Phædrus, p. 271 D-E. [Greek: dei= dê\ tau=ta i(kanô=s noê/santa, meta\ tau=ta theô/menon au)ta\ e)n tai=s pra/xesin o)/nta te kai\ pratto/mena, _o)xe/ôs tê=| ai)sthê/sei du/nasthai e)pakolouthei=n_, ê)\ mêde\ ei)de/nai pô ple/on au)tô=n ô(=n to/te ê)/koue lo/gôn xunô/n.]] [Footnote 106: Plato, Phædrus, p. 270 C.] [Side-note: Plato's _Idéal_ of the Rhetorical Art--involves in part incompatible conditions--the Wise man or philosopher will never be listened to by the public.]