PREFACE 



XVil 



|)iacti('ally cooval with Cu'sar, Constantine, Charlemagne, 

 St. Louis, Charles V, and Victoria; Bacon, Newton, and 

 Darwin are but the younger contemporaries of Thales, 

 i'hito, and Aristotle" 



I\^rhaps this short survey of a great subject will seem 

 ambit ions to many. 15ut evolution means the slow un- 

 I'okling of hidden i^otentialities. We must study pre- 

 Jiistoric man as well as ancient man because the changes 

 wrought in social evolution are so gradual that it is only 

 hy examining the long period that we can become con- 

 scious of their i-eal significance. The change that is ob- 

 servable at the end of a long period is indistinguishaljle 

 in the briefer interval. This is the author's justification 

 for attempting to present as an organic wdiole a subject 

 the divisions of which specialists often find quite baffling. 

 In the etfort to classify and generalize a great body of 

 knowledge, the ' 'clumsy forceps of our minds" always 

 crush the truth a little and mar it. Yet there is a genuine 

 gain from the very effort to attain perspective, although 

 violence may he done to the strict accuracy of certain 

 details. '^I'li(> artist suppresses many things in order to 

 strengthen the general impression that the picture is to 

 make. Thus, ])erhaps, the scientist can learn from his 

 fellow seeker after truth. 



The selected bibliographies which are appended after 

 each cha]^ter constitute the best works on specific points 

 discussed in the course of the chapter. 



The illustrations have been carefully selected and ar- 

 ranged with a view to illuminate certain points made in 

 the text which the average student would otherwise be 

 unable to visualize. The author would have considerable 

 emphasis placed upon this use of tlie illustrations since 

 each has been chosen for a definite purpose. 



