ABSTRACT
As has been pointed out in the foregoing, the power of the authorities of antiquity was broken during the seventeenth century as the result of a series of brilliant scientific discoveries; in its stead natural scientists based their researches upon the knowledge of the mechanical subjection to law which prevails in nature. However, the need was felt for a definite and uniform conception of nature such as Aristoteleanism undeniably possessed and which was lacking in the new systems of thought which took its place. In actual fact these systems, whether they emanated from Descartes, Spinoza, or Leibniz, were quite as dogmatic as Aristoteleanism; they were pure thought-structures, which, although based on the new natural science, were yet by no means capable of satisfactorily solving the problems to which that science gave rise. As far as biology is concerned, while it is true that physicists like Borelli or Perrault had been able with the aid of the newly-discovered mechanical laws to find solutions to a number of pure problems of motion, yet as soon as more complicated processes in the organism, such as the digestion, the circulation, or sense-impressions, had to be considered, the mechanical principle was found wanting; nor had the other branches of physics and even chemistry as yet reached such a state of development that they could be employed as a means of explaining such phenomena as those just mentioned. In these circumstances many a scientist was content merely to study the new facts which had been brought to light as a result of improved experimental technique, but there were others who devoted their lives to seeking firm ground on which to base a uniform explanation of life-phenomena. In modern times it is not easy to appreciate the difficulties with which these biological thinkers had to contend in their efforts to reconcile the individual results of past research work under one common point of view. Uniformity in the conception of nature in our day, of course, rests essentially upon the law of the indestructibility of energy, to which may be added, in the field of biology, the doctrine of the cell as a unit of life. But the theoretical natural science of the seventeenth century tended, instead of to these ideas, to the assumption of the existence of an unknown force as the origin of life and a basis for its continuance. This force could then be conceived of as something either purely mechanical or 175more idealistic; in the former case one was bewildered, since mechanics cannot provide the answer to more than a small fraction of the questions which the new discovery brought to light; while in the latter case there was the risk of reverting to mysticism in one form or another. These natural-scientific speculations from the beginning of the eighteenth century, which we shall now discuss, originated, curiously enough, less from the anatomists and biologists than from the medical practitioners, who sought to base their medical treatment on a general theory of the functions of the body. Of these latter scientists some few have exercised a radical influence even on the general development of biology and therefore deserve to be mentioned in this connexion.
