changes of hue is beauty, because it allows for the eye's own adaptations of its surroundings in the interest of its own functioning. Thus in this case, and to sum up, truth is synonymous with beauty, in so far as beauty is constituted by favorable stimulation of an organ. The further question, how far this vivid treatment of light is of importance for the realization of depth and distance, is not here entered on. <1> Kirschmann, _Univ. of Toronto Studies, Psychol. Series_ No. 4, p. 20. IV The moment we touch upon line-form we are already, in strictness, beyond the elements. For with form enters the motor factor, which cannot be separated from the motor innervations of the whole body. It is possible, however, to abstract for the moment from the form as a unit, and to consider here only what may be called the quality of line. A line may be straight or broken, and if curved, curving continuously or brokenly, etc. That this quality of line is distinct from form may be shown by the simple experiment of turning a spiral--a logarithmic spiral, let us say--in different ways about its focus. The aesthetic effect of the figure is absolutely different in the different positions, and yet the feeling about the character of the line itself seems to remain the same. In what sense, and for what reasons, does this curved line satisfy the demands of the eye? The discussion of this question precipitates us at once into one of the burning controversies of aesthetics, which may perhaps best be dealt with at this point.