The first term of the series being thus determined, the other arts may at once be ranked according to the degree of their affinity with Poetry. Let us begin by distinguishing the different senses to which they appeal; and we shall find that our series proceeds on the principle which biologists, since Gall’s time, have adopted for the classification of the special senses, the principle of decreasing sociability. There are only two senses which can be called esthetic; namely, Sight and Hearing: the others having no power of raising us to Idealization. The sense of smell can, it is true, enable us to associate ideas; but in man it exists too feebly for artistic effects. Hearing and Sight correspond to the two modes of natural language, voice and gesture. From the first arises the art of Music; the second, which however is less esthetic, includes the three arts of form. These are more technical than Music; their field is not so wide, and moreover they stand at a greater distance from poetry; whereas Music remained for a long time identified with it. Another distinction is that the sense to which music appeals performs its function involuntarily; and this is one reason why the emotions which it calls forth are more spontaneous and more deep, though less definite, than in the case where it depends on the will whether we receive the impression or not. Again, the difference between them answers to the distinction of Time and Space. The art of sound represents succession; the arts of form, co-existence. On all these grounds music should certainly be ranked before the other special arts, as the second term of the esthetic series. Its technical difficulties are exaggerated by pedants, whose interest it is to do so; in reality, special training is less needed for its appreciation, and even for its composition, than in the case of either painting or sculpture. Hence it is in every respect more popular and more social. [Painting Sculpture Architecture]