Health and Disease 
we understand it. I produced muscle contraction in a bottle 
thirty-five years ago, and we still do not understand it. 
Crick: ‘That is because the system is genuinely complex. 
The basic reason why we don’t understand muscular contrac- 
tion is that the molecules involved are large, but we don’t have 
to consider them right down to the atomic nuclei; we can des- 
cribe them in terms of molecular structure, and the same applies 
to the genetic material. I agree with you that it is all very 
complicated, but not as complicated as you’re trying to frighten 
us with. 
Bronowski: I am on Crick’s side in this argument. Now I 
want to stress the importance of these hierarchies of organiza- 
tion as levels also of our understanding of complex phenomena. 
Let me explain this. I was interested in Szent-Gy6rgyi’s 
paper because I am in the process of trying to stop being a 
mathematician and trying to become a biologist. There are 
some things I find hard to understand, but there are some things 
I find it hard to understand why biologists don’t understand. 
One of these is that quantum physics is not an isolated method, 
but is a by-product of a wider movement in our thinking. The 
new thought started with Darwin: it is that step-wise or other 
small forms of change become cumulatively fixed in new, stable 
organizations. ‘This, as much as quantum physics, is part of 
statistical thinking. 
Scientific explanation has moved through several stages in 
history. One stage was originated by Hobbes and Newton; 
theirs was the age when causal explanations suddenly clarified 
everything going on in the world. We are living in a time where 
Statistical explanations are coming to have the same impact. 
But since we all grew up in a causal climate we still find it 
difficult to grasp the implications of the statistical outlook. In 
molecular biology, for instance, we have begun to understand 
the “‘geometrization”’ of organisms, but not yet its arithmetical 
implications. Szent-GyGrgyi is saying that when one tries to 
satisfy all the arithmetical demands of the geometry then 
one asks oneself: how on earth do the molecular units ever 
fit together? The answer is, they fit together by statistics. 
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