288 COOK 



ions. Not only is there no common point of view from which 

 evolutionary problems are studied ; there is no agreement re- 

 garding the nature of the problem or the methods by which a 

 solution is to be expected, nor even a general evolutionary 

 language in which discussion may be made intelligible. 



Explanations of such a process as evolution are of many dif- 

 ferent grades or categories. Literary demands were satisfied 

 by a name and a definition ; theologically it was sufficient to 

 substitute the idea of a continuous for an intermittent creation. 

 Philosophy was content with the predication of gradual trans- 

 formations due to natural causes. Even among biologists there 

 are those who appear to have rested content with similar gen- 

 eralities, though some have not failed to appreciate that when 

 Darwin established the probability of biological evolution he 

 opened a multitude of other questions regarding the nature, 

 causes and significance of the process. Realizing at once the 

 importance of his discovery and the difficulty of securing the 

 confidence of either the scientific or the general public, he ex- 

 pended years of labor in the collection of facts and the con- 

 trivance of theories which should increase the plausibility of the 

 main proposition, that plants and animals are variable, both in 

 nature and in domestication, and that the diversity of organic 

 nature was gradually attained through the medium of variations. 



When the causes of a phenomenon are known the sequence of 

 events can be predicted. Theory may then out-run and assist 

 observation. On the other hand, if the causes are out of reach 

 it is obvious that we can not even theorize to advantage without 

 a correct conception of the externals. We must know what 

 takes place before we are in a position to ask why it takes 

 place. In some lines of thought the simple historical concep- 

 tion of continuous evolutionary change greatly assists in the 

 causal explanation of events, but in biology, the home of the 

 evolutionary conception, the sequence is still in doubt and we 

 are still far from the causal stage of knowledge. It is needless, 

 perhaps, to add that the application of false and fictitious 

 biological analogies vitiates much philosophical and sociolog- 

 ical literature. 



Gravitation was not explained by Newton, its behavior was 



