This classification survived in the Aristotelian schools at Padua and elsewhere as late as Zabarella and Campanella. Zabarella, a professor of logic and later of philosophy at Padua from 1564 to 1589, explains at length Averroes's theory that poetics is a form of logic, in a treatise on the nature of logic, published in 1578.[41] He concludes that the two faculties, logic and poetics, are not instruments of philosophy in general, but only of a part of it, for they refer rather to action than to knowledge; that is, they come under Aristotle's category of efficient philosophy. They are not the instruments of useful art or of moral philosophy, the end of which is to make one's self good; but of civil philosophy, the end of which is to make others good. If it be objected that they are [Greek: ton enantion], that is, of both good and evil, it may be answered that their proper end is good. Thus, in the _Symposium_, the true poet is praised; while in the _Republic_ the poets who aim at pleasure and who corrupt their audiences are censured; and Aristotle in his definition of tragedy says that the end of tragedy is to purge the passions and to correct the morals of men (_affectiones animi purgare et mores corrigere_). Even later than Zabarella, we find in the _Poetica_ of Campanella a division of the sciences very similar to that of Savonarola and Varchi. Theology is there placed at the head of all knowledge, in accordance with the mediaeval tradition, while poetics, with dialectic, grammar, and rhetoric, is placed among the logical sciences. Considering _poetica_ as a form of philosophy, another commentator on Aristotle, Maggi (1550), takes great pains to distinguish its various manifestations. _Poetica_ is the art of composing poetry, _poesis_, the poetry composed according to this art, _poeta_, the composer of poetry, and _poema_, a single specimen of poetry.[42] This distinction is an elaboration of two passages in Plutarch and Aphthonius. II. _Poetry as an Imitation of Life_ In the second place, according to the passage from Strabo cited at the beginning of this chapter, poetry introduces us early to life, or, in other words, its subject is human action, and it is what Aristotle calls it, an imitation of human life. This raises two distinct problems. First, what is the meaning of imitation? and what in life is the subject-matter of this imitation? The conception of imitation held by the critics of the Renaissance was that expressed by Aristotle in the ninth chapter of the _Poetics_. The passage is as follows:--