66 THEORETICAL BIOLOGY 



of compromise, and have chosen certain measurements of 

 time and length, which we all employ in our own world as 

 so-called objective measurements. If we are trying to get a 

 teal insight into the worlds of other subjects, we must each of 

 Us refer to these standard measurements the particular world- 

 factors by which we measure things in our own world. 



Since we are as yet without reliable measurements of the 

 kind, I shall limit myself to indicating how, by means of 

 the motion-formula, we may induce the length of the direction- 

 step. The length of the moment is estimated, on the average, 

 as one-tenth of a second. On the dial of a very large clock 

 with minutes of one centimetre in length, the large hand 

 begins to show appreciable movement when I am five metres 

 from it. Now, according to the rule of motion, at least two 

 steps fall within one moment ( =0"i seconds) ; so, if the move- 

 ment is to be perceptible, in one centimetre 1200 must be 

 made to the minute. This gives 120 to the millimetre, and 

 accordingly the length of each step is about 0*01 millimetre 

 at a distance of five metres. 



This is not the place in which to discuss the methods 

 that enable us to make an exact measurement of the interval 

 in space between one place and another, or the interval in time 

 between one moment and another. We shall merely point out 

 that for the first time the possibility is indicated here of 

 expressing in the conventional time- and length-measurements 

 the absolute unity of measurement of the subjective worlds. 



If we should succeed in bringing these absolute subjective 

 measurements into harmony with the objective structure of 

 our sense-organs, there would be some prospect of initiating, 

 by a strictly scientific method, a comparative .cosmology of 

 human beings and the higher animals. Let us take an 

 instance. Suppose that the distance from rod to rod in the 

 human retina corresponds not only to the distance from one 

 place to another, but also to the length of a direction-step 



