precepts under every school, he will find them given, not indeed by me, but by those who have written more ably on the art, and whom I have diligently consulted with regard to different masters, as I shall hereafter mention. My third object was to facilitate an acquaintance with the various styles of painting. The artist or amateur indeed, who has studied the manner of all ages and of every school, on meeting with a picture can very readily assign it, if not to a particular master, at least to a certain style, much as antiquarians, from a consideration of the paper and the characters, are enabled to assign a manuscript to a particular era; or as critics conjecture the age and place in which an anonymous author flourished, from his phraseology. With similar lights we proceed to investigate the school and era of artists; and by a diligent examination of prints, drawings, and other relics belonging to the period, we at length determine the real author. Much of the uncertainty, with regard to pictures, arises from a similitude between the style of different masters: these I collect together under one head, and remark in what one differs from the other. Ambiguity often arises from comparing different works of the same painter, when the style of some of them does not seem to accord with his general manner, nor with the great reputation he may have acquired. On account of such uncertainty, I usually point out the master of each artist, because all at the outset imitate the example offered by their teachers; and I, moreover, note the style formed, and adhered to by each, or abandoned for another manner; I sometimes mark the age in which he lived, and his greater or less assiduity in his profession. By an attentive consideration of such circumstances, we may avoid pronouncing a picture spurious, which may have been painted in old age, or negligently executed. Who, for instance, would receive as genuine all the pictures of Guido, were it not known that he sometimes affected the style of Caracci, of Calvart, or of Caravaggio; and at other times pursued a manner of his own, in which, however, he was often very unequal, as he is known to have painted three or four different pieces in a single day? Who would suppose that the works of Giordano were the production of the same artist, if it were not known that he aspired to diversify his style, by adopting the manner of various ancient artists? These are indeed well known facts, but how many are there yet unnoted that are not unworthy of being related, if we wish to avoid falling into error? Such will be found noticed in my work, among other anecdotes of the various masters, and the different styles.