Handbook of Biological Data

istry. Because we cannot define these forces, philosophers and saints from Aristotle to Driesch have, over the years, assigned names such as "final cause," "the elan vitale," "the entelechy," "the life principle" to this organizing principle. Since we cannot measure this principle by modern techniques, scientists prefer to ignore its existence, although they must necessarily admit its presence. Professor Sinnott makes the very important plea that no one can afford to be dogmatic about this problem. The true scientist is a modest person. He knows full well that he does not know all the answers. There is no reason to believe that we know all the laws of nature, although we may be able to define some of them. New techniques may reveal new laws so that what cannot be defined at present may some day be made clear. In the meantime, it can be argued that mind bears the same relation to behavior as the organizing self-regulatory forces do to growth and development. Moreover, since it is generally accepted that every living organism is something more than the sum of its parts, so Man is not just a physico-chemical system but a marvellous combination of a machine with the qualitative attributes which we call the mind.