It may, however, be objected that the above-mentioned instances refer only to a particular class of individuals. In other minds, it will be said, the world-picture is entirely built up of visual and acoustic elements. It is also impossible to deny that the classification of minds in different types, which modern psychology has introduced, is as legitimate as it is advantageous for the purposes of research. But we can hardly believe that such divisions have in view anything more than a relative predominance of the several psychical elements.[111] It is easily understood that a man in whose store of memory visual or acoustic images occupy the foremost place may be inclined to deny that motor sensations of unconscious copying enter to any extent into his psychical experience. But an exclusively visual world-image, if such a thing is possible, must evidently be not only emotionally poorer, but also intellectually less distinct and less complete, than an intuition, in which such motor elements are included. The importance of motor sensations in the psychology of knowledge is by itself of no æsthetic interest. The question has been touched upon in this connection only because of the illustration which it gives to the imitation theory. If, as we believe is the case, it is really necessary, for the purpose of acquiring a complete comprehension of things and events, to “experience” them—that is to say, to pursue and seize upon them, not only with the particular organ of sense to which they appeal, but also by tracing movements of the whole body, then there is no need to wonder at the universality of the imitative impulse. Imitation does not only, according to this view, facilitate our training in useful activities, and aid us in deriving an æsthetic delight from our sensations: it serves also, and perhaps primarily, as an expedient for the accommodating of ourselves to the external world, and for the explaining of things by reference to ourselves. It is therefore natural that imitative movements should occupy so great a place among the activities of children and primitive men. And we can also understand why this fundamental impulse, which has played so important a part in racial as well as in individual education, may become so great as to be a disease and dominate the whole of conscious life.[112] As children we all imitated before we comprehended, and we have learned to comprehend by imitating.[113] It is only when we have grown familiar by imitation with the most important data of perception that we become capable of appropriating knowledge in a more rational way. Although no adult has any need to resort to external imitation in order to comprehend new impressions, it is still only natural that in a pathological condition he should relapse into the primitive imitative reaction. And it is equally natural that an internal, _i.e._ arrested, imitation should take place in all our perceptions. After this