TIME 57 



one hand we have a sound recurring at intervals ; on the other, 

 an optical phenomenon, the stroke, likewise recurring at 

 intervals. What common basis admits of these two things 

 being interchangeable ? 



It is evident that what they have in common can only be 

 the same change in the process of apperception, a change 

 which appears both when we hear and when we look at written 

 strokes. Since the process of apperception always releases a 

 series of moment-signs, in both cases a change in the filling up 

 of the moment-signs must appear. No attention is given to 

 the fact that the content of the moment-signs is very different 

 in the two cases ; all that is felt as the same subjective act 

 is the regular alternation of filling up and emptying the 

 moment-signs. 



The same subjective act also appears when we innervate 

 our muscles in beating time. In the course of apperception, 

 it always happens that certain moment-signs are noted 

 especially. We call this power of noting certain moment- 

 signs more than others, " attention." And since we describe 

 as rhythm any regularly recurring change whatsoever, we 

 may in the last instance refer the power to form numbers to a 

 rhythm of the attention. Now, according to the length of 

 the interval, there are very different kinds of rhythm, which 

 we distinguish from one another and are able to combine into 

 unities. The so-called lightning-calculators have this faculty 

 in an especially high degree. 



To our attention it is a matter of indifference towards 

 what sort of content it is directed — whether on objects, or 

 sensations, or feelings. As soon as there appears a regular / 

 change in the attention, it can be subjected to the rule of 

 the simplest rhythm, i.e. it can be counted. This peculiarity 

 gives to number its almost unlimited applicability. 



