INTRODUCTION xiii 



" bone-shaker," at one time by the introduc- 

 tion of ball-bearings, at another by the inven- 

 tion of pneumatic tyres, each new make, 

 thanks to this or that better " adaptation," 

 being eminently successful in surviving against 

 its kindred but less developed competitors 

 in the struggle for existence. From bicycle, 

 or similarly motor or aeroplane, we pass 

 readily enough to bicyclist, to racehorse and 

 bird : and we see how we may explain the 

 evolution of their swiftness in like manner. 

 The man in the street is thus a Darwinian 

 without knowing it, and the world-success 

 of Darwin's theory is thus more readily 

 understood; the age had found its man, the 

 hour its voice. 



But what of outdoor nature ? " The field in 

 summer, the study in winter " is a good rule, 

 yet not a sufficient one; the evolutionist's 

 studies should as far as possible include both 

 elements of observation and interpretation 

 day by day. Hence Darwin's is perhaps the 

 most exemplary of scientific lives, incessantly 

 rising from sight to insight, yet this as con- 

 stantly freshening sight anew. From boyish 

 truancies, through youthful travels and matur- 

 ing researches his observations and his specu- 

 lations went on enriching one another; and 

 thus their interpretation and theory have been 



