While Fracastoro strives to elaborate the important passage in Aristotle touching the universal of poetry, and though somewhat vague in his treatment, keeps fairly close to the mark; Castelvetro, on the contrary, judges the Aristotelian fragment with the freedom and superior knowledge of the true critic. He recognizes that the _Poetics_ is merely a notebook recording certain principles and methods of compiling the art, not the art fully compiled. He remarks, moreover, not without logical acumen, that Aristotle having adopted the criterion of probability or of that "which presents an appearance of historic truth," should have applied his theory in the first case to history, not to poetry; for history being a "narrative according to truth of memorable human actions," and poetry a narrative according to probability of events which might possibly occur, the second cannot receive "all its radiance" from the first. Nor does it escape him that Aristotle describes two different things by the one word "imitation": (_a_) "following the example of another," which is "acting in exactly the same way as another without knowing the reason of such action": and (_b_) the imitation "demanded by poetry," which "does things in a manner totally different from that in which they have been done hitherto and proposes a new example for imitation." Nevertheless Castelvetro cannot extricate himself from the confusion between the imaginary and the historical; for he himself says "the realm of the former is generally that of certainty," but "the field of certainty is often crossed with bars of uncertainty just as the field of uncertainty is often crossed with bars of certainty." Also what can be said of this curious interpretation of the Aristotelian theory of pleasure experienced in the imitation of ugly models, that such pleasure is based on the fact that since an imitation is always imperfect, it is incapable of exciting the disgust and fear which would arise from the contemplation of real ugliness? And what of his remark that the characteristics of painting and poetry are so diverse as to be in opposition one to the other; imitation of objects giving rise to great pleasure in the former art and as great displeasure in the latter? And so on in numberless cases of bold but scarcely felicitous subtleties.[29] [Sidenote: _Piccolomini and Pinciano._]