viii PREFACE. 



for M. Mayor lived for more than twenty years in 

 Brooklyn, New York, and received Agassiz at his house 

 when he came to the New World. Each had perfect 

 confidence in the other ; as cousins and friends they 

 loved one another without reserve. For myself, I can- 

 not separate Louis Agassiz from Auguste Mayor. Such 

 friendly and constant relations in both hemispheres 

 between two men are extremely rare. 



I have carefully read and considered all documents, 

 and have made constant use of my intimate knowledge 

 of Agassiz. Scientifically we did not agree on all 

 points; but both were satisfied to accept our differences 

 of opinions. On the whole, our friendship was never 

 shadowed by a single serious disagreement. 



The biography of such a man as Agassiz cannot be 

 given by the publication of his letters only ; because in 

 letters the confidences are not so free, precise, or so 

 full as can be desired : besides, many letters, for various 

 reasons, cannot be published in full. Agassiz's genius 

 was so spontaneous, so frankly natural, so absolutely 

 sincere, that his physiognomy was most attractive, show- 

 ing always the great mobility of his sentiments. He 

 was one of those very few men whose works are not 

 sufficient to make him entirely known ; one must meet 

 him face to face. Agassiz was so full of personal in- 

 spiration and original thought, that in order to have a 

 just idea of him, naturalists went to Neuchatel, and 

 afterward to Cambridge, only to see him, and shake his 

 hand. His individuality was a subject of continual 

 observation by all those who surrounded or approached 

 him. He was of an extremely rare and very complex 



