INTRODUCTION 



Zuwachs an Kentnis ist Zuwachs an Unruhe. 

 Goethe, Aus meinem Leben, 8. Buch 



Our doubts are traitors 

 And make us lose the good we oft might win 

 By fearing to attempt. 



Shakespeare, Measure for Measure 



The division of physics into experimental and theoretical physics is 

 generally accepted. The meaning of this subdivision is well expressed 

 in the British name for theoretical physics: Natural Philosophy. It 

 means that philosophical features are abstracted from the descriptive 

 and experimental facts and formulated in a general vv^ay. In physics 

 the obvious method of doing so is with the help of advanced mathe- 

 matical treatment. 



There is no reason why biological disciplines should not proceed 

 in the same way. But actually theoretical biology has, in most in- 

 stances, tried to consider biological facts in terms of abstract philoso- 

 phy, if not metaphysics, while the general elaboration of laws and 

 rules has been intricately interwoven with the diverse types of factual 

 study. Abstract concepts such as mechanism, vitalism, teleology, 

 holism, creative evolution, and psycholamarckism are the topics of 

 discussion in theoretical biology; but the theoretical aspects, say, of 

 evolution or development are usually discussed with the factual presen- 

 tations as an integral part of the special knowledge. Many biologists 

 are suspicious of generalizations which are not part and parcel, actu- 

 ally a small part, of descriptive or experimental studies. There is even 

 a school of biologists which frowns upon any general ideas beyond 

 the limited topic of the special study. These workers would consider 

 the non-existence of a theoretical biology, comparable to theoretical 

 physics, a very laudable condition. This proves that biology has not 

 yet progressed to the same level as physics, besides not being intrinsi- 

 cally able to generalize in terms of mathematical functions, except in 

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