Preface 



* Physicists are lucky never to have known the 

 method of sections and dyes. What would have 

 been the result if by chance a steam engine had 

 fallen into the hands of a histological physicist ? 

 What thousands of sections horizontal and vertical, 

 stained in various ways, how many diagrams and 

 figures might have been made, without arriving at 

 an indubitable conclusion that the machine is a 

 heat engine and is used to transform heat into 

 motion 1 ' (Quoted by Dastre.) 



This comparison places the characteristics of the 

 two methods in a strong light. 



The method of restricted analyses and profound 

 study of details is extremely useful in scientific research, 

 but is without philosophical value. The method of 

 general synthesis is the only one suitable to scientific 

 philosophy for it alone can bring out what is really 

 important in a given order of facts. The boiler and the 

 motor mechanism are the truly important parts in the 

 steam-engine. W T hen this mechanism has been under- 

 stood there will be no difficulty in understanding the 

 part played in the accessory details, the wheels and the 

 brakes. But it would be folly to seek to understand 

 the locomotive by a study, however complete, of a 

 detached bolt or the spoke of a wheel! 



Psychologists who rest in the systematic study of 

 small facts are obviously like to the ' histological 

 physicists ' : both end in similar impotence. 



I conclude: From the philosophical point of view, 

 (the one to which I confine myself) and in a given 

 order of facts, only the comprehension of the higher 

 facts is important, for it includes, a fortiori, that of all 

 others. Consequently the descending method only, 

 starting from those higher facts, is the fruitful one. 



Moreover, we judge the tree by its fruit: it is, as 

 we shall see, by that method alone that all the phenomena 



xviii 



