THE PLASTICITY OF LIFE 



IN his first Law of Motion, Newton stated that " Every 

 body perseveres in its state of rest, or of uniform 

 motion in a straight line, except in so far as it is compelled 

 by forces to change that state/' In this magnificent 

 truism are summed up two aspects of Nature which are 

 everywhere familiar to us the tendency to persist in a 

 given state or along a given path, and the liability to 

 diverge under the action of incident forces. We may call 

 the one the aspect of inertia, the other the aspect of change. 

 Constancy, continuance, persistence, we see on the one 

 hand ; change, compromise, novelty, on the other. 



Is it not true even of that complex which we call our 

 personality ? Our mental environment, our intellectual 

 furniture, our ruling ideas how they change for better 

 or worse as we live ; but beneath all there is a permanent 

 element a certain style of mental architecture, so to 

 speak which seems to change but little. The child, as 

 we say, is father of the man. 



The twofold impression of novelty and of persistence 

 is familiar in history ; periodically everything seems to 

 become new, there are renaissances ; on the other hand, 

 history repeats itself ; some of the trade-tricks of the 

 Phoenicians or the banking-devices of ancient Babylon 

 recur to-day, and we say, with a sigh, that there is nothing 

 new under the sun. 



We see the same two aspects in the history of that 



complex which we call our body. It is ceaselessly chang- 



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