THE INDIVIDUAL LIFE CYCLE 159 



develops and grows, it shows increasing complexity 

 and division of labour (differentiation) and increasing 

 control and harmony (integration) ; it secures its foot- 

 hold and gains grip ; in short, there is an ascending 

 curve of gradually increasing strength. Then comes 

 a period of mature efficiency, with which reproduc- 

 tivity is usually associated. The creature is at its 

 prime. Sooner or later, however, it begins to relax 

 a little, to weaken, and to grow old. It passes on to 

 the downgrade which ends in death. 



The general fact, then, is a gradual curve upwards 

 from the weakness of early youth to the full strength, 

 and then a gradual curve downwards to the weakness 

 of old age. " And so, from hour to hour, we ripe and 

 ripe, and then, from hour to hour, we rot and rot, 

 and thereby hangs a tale." But just as some animals 

 have a long youth and some a long prime, so in Man 

 the precise shape of the life-curve varies greatly with 

 the individual, and is, in some measure, in his own 

 hands. There are averages, of course, but there is no 

 precise length of years to be reckoned to youth, or 

 to maturity, or to senescence. We have to think of 

 the threads of our life as consisting in part of non- 

 extensible stretches and in part of elastic stretches. 

 The latter, e.g, the stretch of cerebral variability, may 

 be lengthened out or shortened down. Our nature 

 consists of a great many of these threads, and we may 

 stretch out the youth of some of them while we cannot 

 do this for others. In spite of ourselves, sometimes, 

 certain threads in our composition grow old prema- 



