The initial signs from which the work of art is built up psychologically in the case of sculpture differ in several respects from the initial signs of painting. There are of course forms of sculpture for which the difference is slight. Some bas-reliefs, for example, can be considered as essentially drawings, and sculpture placed as a decorative detail in architecture so that it can only be viewed from one angle has necessarily to be interpreted in much the same manner. Similarly some primitive sculpture in which only one aspect is represented may be considered as covered by what has been said about painting, although the fact that the relief and the relation of volumes is more completely given and less supplied by imaginative effort is of some consequence. Further, the changes, slight though they may be, which accompany slight movements of the contemplator have their effect. His total attitude is altered in a way which may or may not be important according to circumstances. With sculpture in which a number (four for example) of aspects are fully treated without any attempt to fill in the intermediate connecting aspects, the whole state of affairs is changed, since there arises the interpretative task of uniting these aspects into a whole. This connection of a number of aspects into a whole may be made in varying ways. The signs may receive a _visual_ interpretation and the form be mainly built up of visual images combined in sequences or fused. This, however, is an unsatisfactory method. It tends to leave out or blur too many of the possible responses to the statue and there is usually something unstable about such syntheses. The form so constructed is insubstantial and incomplete. Thus those sculptors whose work primarily asks for such a visual interpretation are commonly felt to be lacking in what is called a ‘sense of form’. The reasons for this are to be found in the nature of visual imagery and in the necessarily limited character of our purely visual awareness of space. But the connection may be made, not through visual combination, but through combination of the various muscular images whereby we feel, or imaginatively construct the tensions, weights, stresses, etc. of physical objects. Each sequence of visual impressions as we look at the statue from varying standpoints calls up a group of these muscular images, and these images are capable of much more subtle and stable combinations than the corresponding visual images. Thus two visual images which are incompatible with one another may be each accompanied by muscular images (feelings of stress, tension, etc.) which are perfectly compatible and unite to form a coherent whole free from conflict. By this means we may realise the solidity of forms far more perfectly than if we rely upon visual resources alone, and since it is mainly through the character of the statue as a solid that the sculptor works, this muscular interpretation has, as a rule, obvious and overwhelming advantages.