PREFACE. TU 



gers, and regarded the mere laws of their coexistence with 

 brain-states as the ultimate laws for our science. The 

 reader will in vain seek for any closed system in the book. 

 It is mainly a mass of descriptive details, running out into 

 queries which only a metaphysics alive to the weight of 

 her task can hope successfully to deal with. That will 

 perhaps be centuries hence ; and meanwhile the best mark 

 of health that a science can show is this unfinished-seeming 

 front. 



The completion of the book has been so slow that 

 several chapters have been published successively in Mind, 

 the Journal of Speculative Philosophy, the Popular Science 

 Monthly, and Scribner's Magazine. Acknowledgment is 

 made in the proper places. 



The bibliography, I regret to say, is quite unsj^stem- 

 atic. I have habitually given my authority for special 

 experimental facts ; but beyond that I have aimed mainly 

 to cite books that would probably be actually used by 

 the ordinary American college-student in his collateral 

 reading. The bibliography in W. Volkmann von Volkmar's 

 Lehrbuch der Psychologie (1875) is so complete, up to its 

 date, that there is no need of an inferior duplicate. And 

 for more recent references, Sully's Outlines, Dewey's Psy- 

 chology, and Baldwin's Handbook of Psychology may be 

 advantageously used. 



Finally, where one owes to so many, it seems absurd to 

 single out particular creditors ; yet I cannot resist the 

 temptation at the end of my first literary venture to record 

 my gratitude for the inspiration I have got from the writ- 

 ings of J. S. Mill, Lotze, Kenouvier, Hodgson, and Wundt, 

 and from the intellectual companionship (to name only five 

 names) of Chauncey Wright and Charles Peirce in old 

 times, and more recently of Stanley Hall, James Putnam, 

 and Josiah Eoyce. 



Harvakd XJnivebsity, August 1890. 



