AUTHOR'S PREFACE 



For a long time it had been my desire to extend my earlier 

 reading of the Hves and works of scientific investigators, and 

 undertake more comprehensive historical studies; but I had 

 first to pursue to my own satisfaction my aim of trying to be 

 an investigator myself. The time for historical reading 

 gradually arrived and the more I delved into the works and 

 lives of great men, the more it appeared to me that much re- 

 mained to be done beyond what previous histories of scientific 

 research had given us. What most struck me in recent writ- 

 ings on this subject was a want of that understanding of the 

 great men of science which, so it seemed to me, should come 

 from a study of their life history and their behaviour. I 

 found that these scientists - or at least not a few of them, 

 and those the most successful - were much more above the 

 common run of humanity than the most widely read bio- 

 graphies suggested. My joy was great to find that these 

 personalities so well matched the greatness of their achieve- 

 ments, that they were fit to serve as examples to future 

 generations both from the point of view of their work and 

 from that of their lives. 



I therefore thought it well to communicate this satisfaction 

 to others as soon as my studies had progressed sufficiently for 

 me to be sure of my facts, and also to form the whole of them 

 into a picture of the development of science, in which in- 

 dividual workers would occupy a position given by the 

 actual development of themselves and their work. For this 

 purpose a regular plan of study was necessary, which had to 

 comprehend not only the existing historical works on 

 science, but also, and even to a much more important 



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