Sec. 1. It would be easy to find a definition of beauty that should give in a few words a telling paraphrase of the word. We know on excellent authority that beauty is truth, that it is the expression of the ideal, the symbol of divine perfection, and the sensible manifestation of the good. A litany of these titles of honour might easily be compiled, and repeated in praise of our divinity. Such phrases stimulate thought and give us a momentary pleasure, but they hardly bring any permanent enlightenment. A definition that should really define must be nothing less than the exposition of the origin, place, and elements of beauty as an object of human experience. We must learn from it, as far as possible, why, when, and how beauty appears, what conditions an object must fulfil to be beautiful, what elements of our nature make us sensible of beauty, and what the relation is between the constitution of the object and the excitement of our susceptibility. Nothing less will really define beauty or make us understand what aesthetic appreciation is. The definition of beauty in this sense will be the task of this whole book, a task that can be only very imperfectly accomplished within its limits. The historical titles of our subject may give us a hint towards the beginning of such a definition. Many writers of the last century called the philosophy of beauty _Criticism,_ and the word is still retained as the title for the reasoned appreciation of works of art. We could hardly speak, however, of delight in nature as criticism. A sunset is not criticised; it is felt and enjoyed. The word "criticism," used on such an occasion, would emphasize too much the element of deliberate judgment and of comparison with standards. Beauty, although often so described, is seldom so perceived, and all the greatest excellences of nature and art are so far from being approved of by a rule that they themselves furnish the standard and ideal by which critics measure inferior effects. This age of science and of nomenclature has accordingly adopted a more learned word, _Aesthetics,_ that is, the theory of perception or of susceptibility. If criticism is too narrow a word, pointing exclusively to our more artificial judgments, aesthetics seems to be too broad and to include within its sphere all pleasures and pains, if not all perceptions whatsoever. Kant used it, as we know, for his theory of time and space as forms of all perception; and it has at times been narrowed into an equivalent for the philosophy of art.