vi PREFACE TO THE FOURTH EDITION. 



edition of the Principles of Psychology, published in July, 

 1855, mental phenomena are interpreted entirely from the 

 evolution point of view; and the words used in the titles of 

 sundry chapters, imply the presence, at that date, of ideas 

 more widely applied in the Essays just named. As the first 

 edition of The Origin of Species did not make its appear- 

 ance till October, 1859, it is manifest that the theory set 

 forth in this work and its successors, had an origin independ- 

 ent of, and prior to, that which is commonly assumed to 

 have initiated it. 



The distinctness of origin might, indeed, have been in- 

 ferred from the work itself, which deals with Evolution 

 at large — Inorganic, Organic, and Super-organic — in terms 

 of Matter and Motion; and touches but briefly on those 

 particular processes so luminously exhibited by Mr. Dar- 

 win. In § 159 only (p. 447), when illustrating the law 

 of " The Multiplication of Effects," as universally dis- 

 played, have I had occasion to refer to the doctrine set 

 forth in the Origin of Species pointing out that the general 

 cause I had previously assigned for the production of diver- 

 gent varieties of organisms, would not suffice to account 

 for all the facts without that special cause disclosed by 

 Mr. Darwin. The absence of this passage would, of 

 course, leave a serious gap in the general argument; 

 but the remainder of the work would stand exactly as it 

 now does. 



I do not make this explanation in the belief that the 

 prevailing misapprehension will thereby soon be rectified; 

 for I am conscious that, once having become current, wrong 

 beliefs of this kind long persist — all disproofs notwithstand- 

 ing. Nevertheless, I yield to the suggestion that un- 

 less I state the facts as they stand, I shall continue 

 to countenance the misapprehension, and cannot expect it 

 to cease. 



With the exception of unimportant changes in one of 

 the notes, and some typographical corrections, the text of 



