12. The inner fixation-point of the temporal senses differs essentially from the outer fixation-point of the spacial senses, in that its character is primarily determined, not by sensational, but by affective elements. Since these affective elements are continually changing, in consequence of the varying conditions of psychical life, the inner fixation-point is also always changing. This change of the inner fixation-point is called the continuous flow of time . By continuous flow we mean to express the fact that no moment of time is like any other, and that no such moment can return (cf. sup. p. 143, 2 a). This fact is connected with the one-dimensional character of time, which is due to this very circumstance, that the inner fixation-point of temporal ideas is continually moving forward, so that a single point can never recur. The arrangement of time in one dimension, with reference always to a changing point of fixation, in which the subject represents itself, is what gives rise to the result that the elements of time-Ideas have a fixed relation, not only with respect to one another, but also with respect to the ideating subject (p. 143, 2).
13. If we try to give an account of the means for the formation of this reciprocally interdependent order of the parts of an idea, and of their determination in regard to the ideating subject, it is obvious that these means can be nothing but certain of the elements of the idea itself,, which, considered in themselves, have no temporal attributes, but gain such attributes through their union. We may call these elements temporal signs, after the analogy of local signs.
The characteristic conditions for the development of temporal ideas indicate from the first that these temporal signs are, [p. 157] in the main, affective elements. In the course of any rhythmical series every impression is immediately characterized by the concomitant feeling of expectation, while the sensation is of influence only in so far as it arouses the feeling.
This may be clearly perceived when a rhythmical series is suddenly interrupted.
Furthermore, the only sensations that are never absent as components of all time-ideas are the sensation of movement. In the case of tactual ideas these sensations of movement belong to the immediate elements of the ideas themselves, in auditory and other compounds that are brought into the time form, they are always present as subjective accompanying phenomena. We may, accordingly, regard the feelings of expectation as the qualitative, the sensations of movement as the intensive, temporal signs of a temporal idea. The idea itself must then be looked upon as a fusion of the two kinds of temporal signs with each other and with the objective sensations arranged in the temporal form. Thus, the sensations of movement, as a series of intensive sensations, give a uniform measure for the arrangement of the objective sensations as characterized in quality by the concomitant feelings.
13 a. The sensations of movement play a similar part in the formation of both time-ideas and space-ideas.
This like sensational substratum leads very naturally to a recognition of a relation between these two forms of perception, which finds its expression in the geometrical representation of time by a straight line. Still, there is an essential difference between the complex system of temporal signs and the systems of local signs in the fact that the former is based primarily, not on the qualitative attributes of sensations, connected with certain special external sense-organs, but on feelings which may come in exactly the same way from the most widely differing kinds of sensation, since they are not dependent on the objective content of these sensations, but on their subjective synthesis. These characteristics [p. 158] of time-ideas account for the universal significance that we attribute to them. This was what was improperly expressed in the Kantian principle, that time is a "form of the inner sense". This expression is to be criticised on the ground of its erroneous presupposition of an inner sense (p. 8 sq.)
Here again we have the same opposed natativist, and genetic theories on the psychological origin of time-ideas, as we had in the case of spacial-ideas (p. 114, 12a). In this case, however, nativism has never developed a theory in any proper sense. It usually limits itself to the general assumption that time is a "connate form of perception", without attempting to give any account of the influence of the elements and conditions of temporal ideas which can be actually demonstrated. The genetic theories of older psychology, as, for example, that of Herbart, seek to deduce time-perception from ideational elements only. This is, however, pure speculation and loses sight of the conditions given in actual experience.