In accordance with the principle that complete explanation of psychical facts is possible only through the physiological substrate, we have so far kept rather to that field in dealing with the foundations of our pleasure in rhythm. But further description of the rhythmical experience is most natural in psychological terms. There seems, indeed, on principle no ground for the current antithesis, so much emphasized of late, of "psychical" and "motor" theories of rhythm. Attention and expectation are not "psychical" as opposed to "motor." Granting, as no doubt most psychologists would grant, that attention is the psychical analogue of the physiological tendency to motor discharge, then a motor automatism of which one is fully conscious could be described as expectation and its satisfaction. Indeed, the impossibility of a sharp distinction between ideas of movement and movement sensations confirms this view. When expectation has reference to an experience with a movement element in it, the expectation itself contains movement sensations of the kind in question.<1> To say, then, that rhythm is expectation based on the natural functioning of the attention period, is simply to clothe our physiological explanation in terms of psychological description. The usual motor theory is merely one which neglects the primary disposition to rhythm through attention variations, in favor of the sensations of muscular tension (kinaesthetic sensations) which arise IN rhythm, but do not cause it. To say that the impression of rhythm arises only in kinaesthetic sensations begs the question in the way previously noted. Undoubtedly, the period once established, the rhythmic group is held together, felt as a unit, by means of the coordinated movement sensations; but the main problem, the possibility of this first establishment, is not solved by such a motor theory. In other words, the attention theory is the real motor theory. <1> C.M. Hitchcock, "The Psychol. Of Expectation," _Psychol. Rev., Mon. Suppl._, No. 20. Expectation is the "set" of the attention. Automatism is the set of the motor centres. Now as attention is parallel to the condition of the motor centres, we are able to equate expectation and automatic movement. Rhythm is literally embodied expectation, fulfilled. It is therefore easily to be understood that whatever other emotions connect themselves with satisfied expectation are at their ideal poignance in the case of rhythm.