XXIV 



wliile each of these essays has its intrinsic and inde- 

 pendent claims upon the reader's attention, they are all 

 at the same time but parts of a connected and compre- 

 hensive argument. Nearly all of Mr. Spencer's essays 

 have relations more or less direct to the general doc- 

 trine of Evolution — a doctrine which he has probably 

 done more to unfold and illustrate than any other 

 thinker. The papers comprised in the present volume 

 are those which deal ^vith the subject in its most ob- 

 vious and prominent aspects. 



Although the argument contained in the first essay 

 on " Progress ; its Law and Cause," has been published 

 in an amplified form in the author's " First Principles," 

 it has been thought best to prefix it to the present col- 

 lection as a key to the full interpretation of the other 

 essays. 



To those who read this volume its commendation 

 will be superfluous ; we will only say that those who 

 become interested in his course of thought will find it 

 completely elaborated in his new System of Philos- 

 ophy, now in course of publication. 



The remaining articles of Mr. Spencer's first and 

 second series will be shortly published, in a volume en- 

 titled " Essays ; Moral, Political, and ^Esthetic." 



New York, Marc\ 1864. , 



