l62 TIME 



vibrating points becomes in turn the centre of an elementary 

 spherical wave, according to Huyghen's conception. The 

 uniformity of external physical time would thus be a simple 

 concept resting in last analysis on an infinity of individual non- 

 uniform elements, the continuity of which is assured by 

 memory and tradition. 



yfjr^ front 



Zach point <3, b. c, etc. is the origin of<3 vy<3Ye 



FIG. 29. FRONT WAVE CURVE 



It is evident that we do not intend to estabUsh a parallel 

 between the propagation of light waves and time. We have 

 simply tried to clarify the notion of 'envelope'. A parallel 

 could only exist provided each elementary wave issuing from 

 a vibrating centre were damped in such a way as to progress 

 more rapidly at the start than at the end. The discrepancy 

 between the order of magnitude of the small individual waves 

 and that of the envelope bubble is so great that the observer 

 who perceives only the latter ignores its origin. Just as an 

 observer of the universe cannot perceive the difference 

 between the two times unless he succeeds in finding an 

 internal standard of time: the physiological time defined above. 



It seems to me that the extension of this notion of physio- 

 logical time to the notion of appreciation of time is legitimate. 

 On the one hand, our appreciation of time is one of the 

 properties of our consciousness, and our consciousness is 

 dependent on our physiological cellular reactions. It is there- 

 fore logical to admit that all slowing up of the activity of these 

 reactions must result in a modification of our appreciation of 

 time. We have demonstrated the fact that such was the case 

 and, on the other hand, we know that time seems to flow more 

 quickly as we grow older. This is a commonplace observation 



