There is still another celebrated side of the Platonic philosophy which may be considered, namely æsthetics, the knowledge of the beautiful. In respect to this, Plato has in like manner seized the one true thought, that the essence of the beautiful is intellectual, the Idea of reason. When he speaks of a spiritual beauty, he is to be understood in the sense that beauty, as beauty, is sensuous beauty, which is not in some other place—no one knows where; but what is beautiful to the senses is really the spiritual. The case is the same here as it is with his Idea. As the essence and truth of phenomena in general is the Idea, the truth of phenomenal beauty must also be this Idea. The relation to the corporeal, as a relation of the desires, or of pleasure and utility, is no relation to it as the beautiful; it is a relation to it as the sensuous alone, or a relation of particular to particular. But the essence of the beautiful is just the simple Idea of reason present to the sensuous apprehension as a thing; the content of the thing is nothing else than this.[77] The beautiful is essentially of spiritual nature; it is thus not merely a sensuous thing, but reality subject to the form of universality, to the truth. This universal does not, however, retain the form of universality, but the universal is the content whose form is the sensuous mode; and therein lies the determination of the beautiful. In science, the universal has again the form of the universal or of the Notion; but the beautiful appears as an actual thing—or, when put into words, as a popular conception, in which mode the material exists in mind. The nature, essence, and content of the beautiful is recognized and judged by reason alone, as its content is the same as that of Philosophy. But because reason appears in the beautiful in material guise, the beautiful ranks below knowledge, and Plato has for this very reason placed the true manifestation of reason in knowledge, where it is spiritually manifested. This may be regarded as the kernel of Plato’s philosophy. His standpoint is: first, the contingent form of speech, in which men of noble and unfettered nature converse without other interest than that of the theory which is being worked out; secondly, led on by the content, they reach the deepest Notions and the finest thoughts, like jewels on which one stumbles, if not exactly in a sandy desert, yet at least upon the arid path; in the third place, no systematic connection is to be found, though one interest is the source of all; in the fourth place, the subjectivity of the Notion is lacking throughout; but in the fifth place, the substantial Idea forms the principle.