252 EVOLUTION AND THE PRESENT AGE 
The remembrance of it, indeed, hovers over many a 
system of ancient mythology, where the Prometheus 
who brings to mankind the good gift of fire is apt to 
be associated with the Dionysus who teaches him how 
to ferment his drinks. A great step forward it was 
when the invention of the bow and arrow enabled him 
to slay his foes at a distance, and greatly increase his 
supply of game; another great step it was when the 
water-tight baskets, and still better, the kettle of baked 
clay, enabled him to boil his roots and herbs, his fish 
and flesh; all these were stages in progress that mark 
long eras in that remote past which we call the Stone 
Age, | 
During all those weary stages man could control 
only such mechanical force as was supplied by his 
own muscles, eked out here and there by the rudest 
forms of lever and wedge, roller and pulley, such as 
are found in the absence of tools, or perhaps by 
the physical strength of his fellow-men, if he were so 
fortunate as to control it. But a time came when man 
learned how to turn to his own uses the gigantic 
strength of oxen and horses, and when that day came 
it was such an era as the world had never before wit- 
nessed. So great and so manifold were the results of 
this advancement, that doubtless they furnished the 
principal explanation of the fact that the human race 
developed so much more rapidly in the eastern hemi- 
sphere than in the western. In my book on the Dis- 
covery of America, I have shown that at the time when 
the western hemisphere was visited by the Europeans 
of the sixteenth century after Christ its foremost races, 
in the highlands of Mexico, Central America, and Peru, 
had in respect of material progress reached a point 
