FOREWORD :^\^A« 



In this book, Lecomte du Noiiy discusses an aspect of our- 

 selves, which is both very important and little known — our 

 duration. To endure is an essential characteristic of all 

 living organisms. Time is, in fact, the fabric of life. In his 

 admirable "Creative Evolution," Bergson has shown the 

 fundamental importance of time in biological phenomena. 

 "Wherever anything lives, there is, open somewhere, a 

 register in which time is being inscribed." But the time of 

 our body is not the same as physical time, that is, the time 

 marked by a clock. Physical time is an aspect of the cosmic 

 world. Inward time, an aspect of ourselves. It differs as much 

 from physical time as the solar system differs from a man. 

 It is identical with the living body. For this reason, Lecomte 

 du Noiiy has united in the title of his book the ideas of life 

 and time. It is impossible to understand the nature of our 

 time if we ignore the nature of organic phenomena. Time 

 and life are one and the same thing. A better knowledge of 

 human duration will permit a more effective application of 

 the factors of our environment to the development of our 

 physiological and mental life. 



Physiological time, like physical time, is the expression of 

 certain intrinsic changes within a system. While physical 

 time depends on the motion of the earth around the sun, 

 inner time is bound to some modifications of our humors 

 and tissues. These modifications constitute aging. Of course, 

 aging is an extremely well known phenomenon. But we have 

 only recently learned how to analyze it. In this book, 

 methods are described for the measurement of physiological 

 time, and for the study of its characteristics. Physiological 

 time has been estimated in two different ways: By the rate 

 of wound healing, and by chemical changes taking place in 

 blood serum. The first method was invented by Lecomte du 



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