32 THE LIFE OF SCIENCE 



not differ much from Tannery's, except that I attach more im- 

 portance to the psycho-sociological point of view. 



Auguste Comte had noticed all the bonds that unite the differ- 

 ent sciences, but he did not give enough attention to them. If he 

 had understood that these interactions and this interdependence 

 have existed in all directions from the very beginnings of science, 

 would not the rigid framework of his Cours de philosophie have 

 burst asunder? 



On the other hand, some people seem to think that it is impos- 

 sible to write the history of science as a whole, that the subject is 

 too great. I should rather say that the impossibility is to pick out 

 from this inextricable network the development of one single 

 branch of human knowledge. Moreover, it is actually impossible to 

 write the history of any important discovery without writing, 

 willingly or not, a chapter of the history of science — I mean the 

 history of science as a whole. How could we explain, for instance, 

 the discovery of the circulation of the blood if we did not explain 

 the evolution of anatomy, of comparative zoology, of general 

 biology, of natural philosophy, of chemistry, of mechanics? Like- 

 wise, to make clear how the determination of longitudes at sea 

 was discovered, little by little, we have to resort to the history of 

 pure and applied mathematics, the history of astronomy and navi- 

 gation, the history of watch-making, etc. It would be easy enough 

 to give more examples of the same kind. 



Further, it is only by considering the history of science as a 

 whole that one can appraise the scientific level of a definite period 

 or of a definite country. It has happened more than once that one 

 science became neglected while others were thriving, or that 

 scientific culture moved from one country to another. But the his- 

 torian is not deluded by these facts, and he does not think that 

 human genius is suddenly quenched or rekindled; from his syn- 

 thetical standpoint he sees the torch of light pass from one science 

 to the other or from one people to another. He perceives better 

 than anybody else the continuity of science in space and time, and 

 he is better able to estimate the progress of mankind. 



