yi INTRODUCTION 



coveted treasure mentioned in old-book catalogues, it 

 would be snapped up by another and never delight his eyes. 

 But such was not to be the case. In due time it came 

 (pages uncut) and then what keen delight was his as he 

 devoured page after page, marveling more and more at 

 the wonderful breadth and perspicacity of the presenta- 

 tion. Pasteur seemed alive in its pages, and Duclaux 

 not less alive. No book about a scientific man ever in- 

 terested him more, or could be written, it seemed, with a 

 more appreciative and discriminating touch. When the 

 last page was finished nothing was more natural, there- 

 fore, than to write on its margin : " The most useful book 

 I have read in a long time." 



Going over these pages ten years later, the writer sees 

 no reason for modifying his first judgment. The next 

 impulse was to lend the book, and then to wish that it 

 might reach thousands of readers in a suitable English 

 dress. This idea disturbed his spirit so much that finally 

 he began a translation, dictating to a stenographer in the 

 odd minutes of a busy life. Later, it seemed better to 

 turn over a part of this work to an assistant. Eventu- 

 ally, about two-thirds of the rough draft from the French 

 was made by Florence Hedges. We then worked it over 

 together into its present English shape, but those who 

 can read it in the French are advised to do so, since, do 

 the best we could, Duclaux's wonderful idiomatic style 

 has lost somewhat in the translation. 



If Pasteur be an incomparable genius, Duclaux, at 

 least, is his Boswell, but he is more than a mere Boswell 

 tagging around after a great man. He is himself a great 

 man. He has a genius of his own which burns with a very 

 clear flame a genius that penetrates and illuminates 

 whatever it touches, and this has made him an incompar- 

 able biographer, and one of an unusual kind. He is no 

 blind partisan or patriot. He thinks his own thoughts, 



