THE ERA OF HELPLESSNESS 69 



natural selection affects both sexes, and the small 

 margin possessed by each individual joining in the 

 reproductive act gives to the offspring an hereditary 

 tendency of two such small margins. The old story 

 of the grains of wheat asked for by the inventor of 

 the game of chess is a striking illustration of the 

 stupendous cumulative possibilities of such a process 

 of addition, which makes progress as the powers of 

 two. 1 The nature of this incentive will be discussed 

 in Chapter III. See Appendix, Note V, on the rela- 

 tion between brain weight and intelligence. 



1 The story runs that the inventor, when requested to name 

 his own reward, asked for two grains of wheat for the first square, 

 double that for the second, double that for the third, and so on to 

 the sixty-fourth. To express, in grains of wheat, the price of 

 the sixty-fourth square, requires a figure of twenty-two integrals, 

 and by doubling this figure the price of all the sixty-four squares 

 is obtained. From an estimate of 200 grains of wheat to the 

 cubic inch, obtained by trial, it follows that for 1,000,000 grains 

 it takes three cubic feet, and the whole number of grains of 

 wheat necessary to pay the reward requires a space of 20,000,- 

 000 cubic miles to contain them. To form an idea of so enor- 

 mous a quantity of wheat, it may be helpful to state that it would 

 be sufficient to cover the whole surface of the earth, both land 

 and water, to a depth of about 300 feet. 



