PEE FACE. 



As the plan of this work is fully given in the Introduction, 

 only a few points, chiefly of a personal character, remain to 

 be touched on here. 



The first refers to the motive which led me to a course 

 of studies, extending over more than thirty years, of which 

 this book is the outcome. 



The object of the book is philosophical, in the sense now 

 accepted by many and by divergent schools i.e., it desires 

 to contribute something towards a unification of thought. 

 "When in the beginning of my philosophical studies I be- 

 came convinced that this is the task of philosophy, I felt 

 the necessity of making myself acquainted, at first hand, 

 with the many trains of reasoning by which, in the 

 separate domains of science, of practical and of individual 

 thought, such a unification has been partially and success- 

 fully attempted. Such a survey seemed to me indispens- 

 able. The possession of a map showing the many lines of 

 thought which our age has cultivated seemed to me the 

 first requisite, the basis from which a more complete 



