INTRODUCTION. 415 



order of his time and nation, therefore, gave 

 to Darwin the push to his task, and suggested 

 to him his epochal thought. 



A few indications may be pointed out. 

 Kicardo's Theory of Rent made a great stir 

 in England during Darwin's earlier days, and 

 was generally accepted. This showed a selec- 

 tion of the land, the best being taken first, then 

 the next best, till the poorest soil was reached 

 which would simply furnish food enough to 

 keep those alive who tilled it. But the peo- 

 ple needing bread would still increase; what 

 was to become of them? At least they would 

 have to engage in the bitter struggle for ex- 

 istence, which Darwin saw raging around him 

 on every side, and which became a part of his 

 consciousness. Then Britain was an island 

 whose territorial limits could not only be seen 

 but decidedly felt, so that they have entered 

 into the very character of the Englishman who 

 has so often been designated as insular. Thus 

 Nature had drawn a sea-line around the sup- 

 ply of food though the mouths to be fed kept 

 increasing. Necessarily the impressive social 

 phenomenon in the British Isles was the strug- 

 gle for existence. But the most significant of 

 all books to Darwin in his mood was the Es- 

 say on Population by Malthus. This brings 

 out that while sustenance increases only in 

 arithmetical ratio, population increases at the 



