_Esthetics_, or the _Philosophy of the Fine Arts_, is that department of philosophy which studies the conception of the _beautiful_ and its external expression in the works of nature and of man. The arts themselves, of course, whether concerned with the realization of the useful or of the beautiful, are distinct from sciences, even from practical sciences.(13) The _technique_ itself consists in a skill acquired by practice—by practice guided, however, by a set of practical canons or rules which are the ripe fruit of experience.(14) But behind every art there is always some background of more or less speculative truth. The conception of the _useful_, however which underlies the mechanical arts and crafts, is not an ultimate conception calling for any further analysis than it receives in the various special sciences and in metaphysics. But the conception of the _beautiful_ does seem to demand a special philosophical consideration. On the subjective or mental side the esthetic sense, artistic taste, the sentiment of the beautiful, the complex emotions accompanying such experience; on the objective side the elements or factors requisite to produce this experience; the relation of the esthetic to the moral, of the beautiful to the good and the true—these are all distinctly philosophical questions. Up to the present time, however, their treatment has been divided between the other departments of philosophy—psychology, cosmology, natural theology, general metaphysics, ethics—rather than grouped together to form an additional distinct department. V. DEPARTMENTS OF SPECULATIVE PHILOSOPHY: METAPHYSICS.—The philosophy which studies the order realized in things apart from our activity, speculative philosophy, has been variously divided up into separate departments from the first origins of philosophical speculation. When we remember that all intellectual knowledge of things involves the apprehension of _general_ truths or laws about these things, and that this apprehension of intelligible aspects common to a more or less extensive group of things involves the exercise of _abstraction_, we can understand how the whole domain of speculative knowledge, whether scientific or philosophical, can be differentiated into certain layers or levels, so to speak, according to various degrees of abstractness and universality in the intelligible aspects under which the data of our experience may be considered. On this principle Aristotle and the scholastics divided all speculative knowledge into three great domains, _Physics_, _Mathematics_ and _Metaphysics_, with their respective proper objects, _Change_, _Quantity_ and _Being_, objects which are successively apprehended in three great stages of abstraction traversed by the human mind in its effort to understand and explain the Universal Order of things.