vi PREFACE. 



to which I have just alluded, if in no other way, 

 at least by stating correctly the facts of the case. 

 I do not, however, undertake to write a full biography 

 of the great philosopher, or to give a detailed 

 account of his numerous contributions to the scientific 

 literature of his day ; I confine myself principally to 

 those great crises in his life which have given rise to 

 so much discussion, and which have chiefly con- 

 tributed to make him a name in history. 



