Thus Benedetto Croce rightly argues that in order to _appreciate_ the artistic works of bygone and extinct nations, it is necessary to have a knowledge and understanding of their life and history--in other words, of their values.[79] What he does not point out, however, and what seems very important, is, that such historical research would be quite unnecessary to one who by nature was _a priori_ in sympathy with the values of an extinct nation; and also, that all the historical knowledge available could not make any one whose character was not a little Periclean or Egyptian from the start, admire, or even appreciate, either the Parthenon, or the brilliant diorite statue of King Khephrën in the Cairo Museum. All great ruler-art, then, is, as it were, a song of praise, a magnificat, appealing only to those, and pleasing only those, who feel in sympathy with the values which it advocates. And that is why all art of any importance, and of any worth, must be based upon a certain group of values--in other words, must have a philosophy or a particular view of the world as its foundation. Otherwise it is pointless, meaningless, and divorced from life. Otherwise it is acting, sentimental nonsense, or _l'art pour l'art_. All great ruler-art also takes Man as its content; because human values are the only values that concern it. All great ruler-art also takes beauty within a certain people as its aim; because the will-to-power is its driving instinct, and beauty, being the most difficulty thing to achieve, is the strongest test of power. Finally, all great ruler-art is optimistic; because it implies the will of the artist to prevail. But what constitutes the form of the ruler-artist's work? In what way must he give us his content? The ruler-artist's form is the form of the commander. It must scorn to please.[80] It must brook no disobedience and no insubordination, save among those of its beholders about whom it does not care, from whom it would fain separate itself, and among whom it is not with its peers. It must be authoritative, extremely simple, irrefutable, full of restraint, and as repetitive as a Mohammedan prayer. It must point to essentials, it must select essentials, and it must transfigure essentials. The presence of non-essentials in a work of art is sufficient to put it at once upon a very low plane. For what matters above all is that the ruler-artist should prevail in concepts, and in order to do this his work must contain the definite statement of the value he sets upon all that he most cherishes. Hence the belief all through the history of æsthetic that high art is a certain unity in variety, a certain single idea exhaled from a more or less complex whole, or, as the Japanese say, "repetition with a modicum of variation."[81]