CHAPTER V 



BIOLOGICAL SPECULATIONS AND CONTROVERSIAL QUESTIONS AT 

 THE BEGINNING OF THE EIGHTEENTH CENTURY 



AS HAS BEEN POINTED OUT it! the fofcgoing, the power of the authori- 

 ties of antiquity was broken during the seventeenth century as the 

 L result of a series of brilliant scientific discoveries; in its stead nat- 

 ural scientists based their researches upon the knowledge of the mechani- 

 cal 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 Aristote- 

 leanism; they were pure thought-structures, which, although based on the 

 new natural science, were yet by no means capable of satisfactorily solv- 

 ing the problems to which that science gave rise. As far as biology is con- 

 cerned, 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 want- 

 ing; 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 ex- 

 plaining 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 con- 

 tend 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 



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