THE EARLIER WORLD 7 



are used to sense grass with in the dark, and 

 the whole instrument is wondrously designed 

 to select sweet grasses, rejecting poisonous or 

 unwholesome plants, so that feeding goes on 

 through hours of total darkness. 



Had the Earth remained an unbroken forest 

 under a roof of cloud there had been no change 

 since the Age of Dragons, no mighty drama of 

 Creation lifting man and horse out of the 

 shadows to work together as master and ser- 

 vant in the conquest and taming of the wilder- 

 ness and final subjugation of the World. 



The one great factor in Earth's history is 

 the lessening of the sun's heat. Through long 

 revolving ages the heat which the Earth re- 

 ceived from the sun diminished. Ever less 

 vapour was lifted from the Equatorial seas, 

 the world-roof of cloud thinned out and dis- 

 appeared ; direct sunshine poured down instead 

 of the endless rains ; there was no moisture 

 left to nourish the worldwide forest. Little 

 by little glades opened in the woodlands 

 caused by drought, savannahs replaced the 

 timber, of tall jungle grasses, the openings 

 widened into prairies, and vast grassy steppes, 

 thousands of miles in breadth, evolved at 

 their centres an aching core of desert. So we 

 have reached the phase when forest, prairie 



