The difference between the first of these is obvious. The history of art and literature has the works of art themselves for principal subject; the other branches of study call upon and interrogate works of art, but only as witnesses, from which to discover the truth of facts which are not aesthetic. The second difference to which we have referred may seem less profound. However, it is very great. Erudition devoted to rendering clear again the understanding of works of art, aims simply at making appear a certain internal fact, an aesthetic reproduction. Artistic and literary history, on the other hand, does not appear until such reproduction has been obtained. It demands, therefore, further labour. Like all other history, its object is to record precisely such facts as have really taken place, that is, artistic and literary facts. A man who, after having acquired the requisite historical erudition, reproduces in himself and tastes a work of art, may remain simply a man of taste, or express at the most his own feeling, with an exclamation of beautiful or ugly. This does not suffice for the making of a historian of literature and art. There is further need that the simple act of reproduction be followed in him by a second internal operation. What is this new operation? It is, in its turn, an expression: the expression of the reproduction; the historical description, exposition, or representation. There is this difference, then, between the man of taste and the historian: the first merely reproduces in his spirit the work of art; the second, after having reproduced it, represents it historically, thus applying to it those categories by which, as we know, history is differentiated from pure art. Artistic and literary history is, therefore, _a historical work of art founded upon one or more works of art_.