vi PREFACE. 



place, in a true light, in correct perspective, with its 

 lights and shadows, in the field of the history of natural 

 science. 



I have tried to speak of him uninfluenced by the dis- 

 cordant voices which have celebrated his merits without 

 discretion, or demolished his reputation without meas- 

 ure. His faults were small, while his genius was great. 

 " Son envergure immense allant d'un bout a 1'autre du 

 ciel scientifique," as was said also of Humboldt and 

 Cuvier. 



I enjoyed his friendship during almost thirty years, 

 being one of the few men to whom Agassiz half 

 unbosomed himself ; and I am the last survivor of the 

 small band of European naturalists who came to Amer- 

 ica with him. My admiration of the man is not con- 

 cealed ; but I have had constantly in view the truth, and 

 have tried to be just, not only towards him, but also 

 towards all those who were more or less connected with 

 him during his scientific life. 



In the thought of many, a man of genius ought to 

 be perfect ; and consequently when errors, mistakes, 

 and faults appear, it is difficult to accept them and 

 bear them with equanimity and indulgence. But we 

 must be generous, and make a fair allowance for human 

 weakness, even in a man of genius, and especially in 

 a man of genius. 



Agassiz kept up all his life a very large correspond- 

 ence, either directly, or when too busy or in ill health, 

 by dictation. In Neuchatel he wrote at least five let- 

 ters daily, not only to naturalists, savants in general, 

 and to his relatives, but also to other friends, and 



