LAWS OF MULTIPLICATION. 289 



different social castes or occupations, the same holds good ; 

 while the prevalence of high multiplication in races of which 

 the nutrition is in obvious excess over the expenditure is also 

 evident, witness the Boers or French Canadians. Such an 

 apparent difficulty as that of the Irish, in whom rapid multipli- 

 cation occurs despite poor food, is accounted for by the re- 

 latively low expenditure in obtaining it (since the " law of 

 diminishing return " imphes its converse for diminishing labour), 

 though, no doubt, also in part by the habit of early marriage, if 

 not by some measure of lowered individuation as well. The 

 main position being established, Spencer proceeds to discuss 

 the question of human population in the future, and. insists 

 strongly on the importance of pressure of population, which he 

 regards as the main incentive to progress alike in past, present, 

 and future. Reviewing the possibilities of progress in bulk, 

 complexity of structure, multiplication and variation of func- 

 tion, he concludes that the more complete moving equilibrium, 

 and more perfect correspondence between organism and 

 environment, which such evolution involves, must take place 

 mainly in the direction of psychical development. Yet this 

 development, while stimulated by pressure of population, con- 

 stantly tends to diminish the rate of fertility ; in other words, 

 this cause of progress tends to disappear as it achieves its full 

 effect. The acute pressure of population, with its attendant 

 evils, thus tends to cease as a more and more highly individu- 

 ated race busies itself with its increasingly complex yet normal 

 and pleasurable activities, its rate of reproduction meanwhile 

 descending towards that minimum required to make good its 

 inevitable losses. 



§ 5. Sumviary of the Population Question.— -^\\q. general 

 question, so far as yet developed, may now be conveniently 

 summarised in the accompanying tabular form. Here the 

 stage of knowledge reached by each author, together with 

 any practical applications therefrom deduced, may be read 

 horizontally, while the historic development of each separate 

 line of conceptions may be traced vertically. 



From such a summary, brief as it is, the main steps in the 

 development of our knowledge are clear enough, but a deeper 

 analysis is required before final exposition or complete appli- 

 cation is possible. Nor, when we note how vast the progress 

 of science through the advance in precision and extension 



