A most important form of fusion consists of the impressions of our sense of hearing and of our organs of locomotion. These impressions are the intermediaries of our ideas of time. If we divide up into their elements the processes of consciousness caused by metronome beats of a medium rapidity, we find two classes--those that belong to the class of sensations and those that belong to feelings. As sensations we have first of all the single metronome beats divided from each other by empty intervals. These are not the only sensations. As we have shown above, there is also a weak sensation of strain which probably arises from the tensor muscle of the tympanum, and which lasts continuously from one beat to the other. To this is joined a further sensation in the mimic muscles surrounding the ear. The whole process, therefore, looked at from the point of view of sensation, appears as a continuous sensation-process, which is interrupted at regular intervals by stronger impulses arising from the objective impressions of the beats. To all this, however, as we saw before, there is added the regularly alternating feelings of strain and relaxation, which determine the rhythmical ideas. All these elements of sensation and feeling form in reality an indivisible whole. If a temporal idea is to arise, none of these components may be wanting, if the sensations are wanting, the feelings have, so to speak, no foundation. They can only arise if sensation impressions are present, upon which the feelings of expectation and realisation can be founded. On the other land the sensations remain unconnected, they lack a combination into a successive row, if the feelings of strain and relaxation are not present, for they directly help in the apprehension of the equality or inequality of the successive periods of time. If the beats are allowed to follow each other so slowly that the last one disappears out of the scope of consciousness when the new one enters, then the idea of time becomes absolutely uncertain. The same thing happens if, on the other hand, the time is so rapid that feelings of strain and relaxation cannot arise. In both cases it is obvious that any uncertain idea of time is only possible by reason of other extraneous factors. Just as all our objective measures of time, from the course of the sun to the vibrations of a tuning-fork used to measure time, depend upon regular periodic movements, so also is our subjective time-consciousness absolutely dependent upon rhythmical ideas. These arise first of all from our movements of locomotion, and then in a much richer and finer form are transmitted to us by our sense of hearing. In all these cases, however, the resulting idea of time can be divided up into a substratum of sensation and into an affective process of strain and relaxation, of expectation and realisation. In the idea of time they fuse perfectly together, so that the influence of these factors can only be shown by