 Second, Herder holds that genre—i.e., a certain set of purposes and rules—is an essential aspect of any work of literature or art. But he also holds that genres differ in deep ways between historical periods (as well as between cultures and even individuals), and this not only in the sense that new genres emerge and old ones die, but also in the sense that seeming continuities in genre typically in fact mask important differences. For example, in the essay Shakespeare (1773) he argues in detail that the genres of ancient Greek “tragedy” and Shakespearean “tragedy”, which interpreters have often assumed to be the same, are in fact deeply different from each other, constituted by different purposes and rules. Similarly, in This Too a Philosophy of History (1774), he argues, against Winckelmann, who had tended to assimilate the genres of ancient Greek portrait sculpture and Pharaonic Egyptian portrait sculpture, that whereas the former was dominated by the genre-purpose of portraying this-worldly life, charm, and beauty, the latter had the quite contrary genre-purpose of conveying ideas of death and eternity.