Without entering further into the scientific merits or demerits of this chapter on the "First Class of Dioptrical Colours," it is to be observed that several of the examples correspond with the observations of Leonardo da Vinci, and again with those of a much older authority, namely, Aristotle. Goethe himself admits, and it has been remarked by others, that his theory, in many respects, closely resembles that of Aristotle: indeed he confesses[1] that at one time he had an intention of merely paraphrasing that philosopher's Treatise on Colours.[2] We have already remarked (Note on par. 150) that Goethe's notion with regard to the production of warm colours, by the interposition of dark transparent mediums before a light ground, agrees with the practice of the best schools in colouring; and it is not impossible that the same reasons which may make this part of the doctrine generally acceptable to artists now, may have recommended the very similar theory of Aristotle to the painters of the fifteenth and sixteenth centuries: at all events, it appears that the ancient theory was known to those painters. It is unnecessary to dwell on the fact that the doctrines of Aristotle were enthusiastically embraced and generally inculcated at the period in question;[3] but it has not been observed that the Italian writers who translated, paraphrased, and commented on Aristotle's Treatise on Colours in particular, were in several instances the personal friends of distinguished painters. Celio Calcagnini[4] had the highest admiration for Raphael; Lodovico Dolce[5] was the eulogist of Titian; Portius,[6] whose amicable relations with the Florentine painters may be inferred from various circumstances, lectured at Florence on the Aristotelian doctrines early in the sixteenth century. The Italian translations were later, but still prove that these studies were undertaken with reference to the arts, for one of them is dedicated to the painter Cigoli.[7] The writers on art, from Leon Battista Alberti to Borghini, without mentioning later authorities, either tacitly coincide with the Aristotelian doctrine, or openly profess to explain it. It is true this is not always done in the clearest manner, and some of these writers might say with Lodovico Dolce, "I speak of colours, not as a painter, for that would be the province of the divine Titian."