Another disciple of Baumgarten, Mendelssohn, conceiving beauty as "indistinct image of a perfection," deduced that God can have no perception of beauty, as this is merely a phenomenon of human imperfection. According to him a primary form of pleasure is that of the senses, arising from "the bettered state of our bodily constitution"; a secondary form is the æsthetic fact of sensible beauty, that is to say, unity in variety; a third form is perfection, or harmony in variety.[44] He too repudiates Hutcheson's _deus ex machina,_ the sense of beauty. Sensible beauty, perfection such as can be apprehended by the senses, is independent of the fact that the object represented is beautiful or ugly, good or bad by nature; it suffices that it leaves us not indifferent: whence Mendelssohn agrees with Baumgarten's definition, "a poem is a discourse sensibly perfect."[45] Elias Schlegel (1742) conceived art as imitation, not so servile as to seem a copy, but having similarity rather than identity with nature: he considered the duty of poetry was first to please and only afterwards to instruct.[46] Treatises on Æsthetic, university lectures or slender volumes for use of the public, _Theories of the Fine Arts and Letters, Manuals, Sketches, Texts, Principles, Introductions, Lectures, Essays,_ and _Considerations on Taste_ poured down thick and fast on Germany during the second half of the eighteenth century. There are at least thirty full or complete treatises and many dozens of minor tracts or fragments. After the Protestant universities, the Catholic took up the new science, which was taught by Riedel at Vienna, Herwigh at Würzburg, Ladrone at Mainz, Jacobi at Freiburg, and by others at Ingolstadt after the expulsion of the Jesuits.[47] A pretty little volume on the _First Principles of the Fine Arts_[48] was written (1790) for Catholic schools by the notorious Franciscan friar Eulogius Schneider, who, after being unfrocked, terrorised Strasburg in the days of the Convention, and met his end under the guillotine. The frenzied output of these German _Æsthetics_ resembles that of _Poetics_ in Italy in the sixteenth century, after the rise to popularity of Aristotle's treatise. Between 1771 and 1774 the Swiss Sulzer brought out his great æsthetic encyclopædia, _The General Theory of the Fine Arts,_ in alphabetical order, with historical notes upon each article, which were greatly enlarged in the second edition of 1792, edited by a retired Prussian captain, von Blankenburg.[49] In 1799, one J. Roller published a first _Sketch of the History of Æsthetic,_[50] in which he observes not unjustly, "Patriotic youth will be pleased to recognize that Germany has produced more literature on this subject than any other country."[51] [Sidenote: _Eberhard and Eschenburg._]