The Promise of Medical Science 
One of the major difficulties of thinking about all these 
problems is the fact that many of the most complex structures, 
as, for instance, the many pathways in our brain, are built when 
they are not yet needed, and that the astounding potentialities 
of the living system are revealed only when they are called upon. 
A cut nerve will find its severed end; a leg, in lower animals, 
may be regenerated from cells which were not meant to become 
a leg. Cells in the plant, made to form leaves, may turn into 
flowers and produce seed, once they have been acted upon by 
hormones produced by other leaves. My brain, with a feeling 
of complete impotence, simply refuses to try to make a picture 
of the mechanism of these phenomena. 
I have spoken only about the difficulties and not the promise 
of medicine. What I wanted to convey is that I think that we 
can expect three great periods in the future history of biology 
and medicine. The first is the continuation of the present one, 
that of molecular biology, which is still far from having run its 
course. The next great period I expect to come from the 
application of wave mechanics to biology. This period has 
already made most hopeful beginnings, but may depend, for its 
full development, on progress still to be made in the parent 
science of physics. My feeling is that beyond all this lies a third 
period which may depend, for its initiation, on hitherto un- 
known physical principles, or on a far-advanced refinement of 
our present knowledge, which will then open the way to the 
understanding of the deepest problems, the nature of life, how 
it originated and perfected itself. 
You may feel disappointed that I have not mentioned any 
single lines of progress in medicine which will flow from the 
broadening of the foundation of biology. I give you a free hand. 
You may wish for anything: a cure-all for cancer, a mastery of 
mutation, an understanding of hormone action, or a cure for 
any of the diseases you have especially in mind. None of your 
wishes need remain unfulfilled, once we have penetrated deep 
enough into the foundations of life. This is the real promise of 
medicine. 
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