2 9 o DEVELOPMENT AND PURPOSE CHAP. 



of the conditions of its life as the utmost extension of 

 knowledge renders possible. What are the limits of 

 this control? May they not be seriously cramping? 

 May there not be biological laws recalcitrant against 

 control, which introduce an insuperable obstacle even to the 

 work of social harmonisa-tion and ultimately engender an 

 arrest and decay on the large scale, as history shows us 

 instances of arrest and decay on the partial scale ? Beyond 

 these, are there not physical conditions, the dissipation of 

 energy, the cooling off of the earth, which we can never 

 control, and which stand as an ahe terminus haerens to all 

 progressive movement, and even to the span of conscious 

 life? Of the positive evidence of such conditions I shall 

 say little. I note that within my own lifetime some of the 

 barriers supposed to be most adamantine have crumbled 

 before the advance of knowledge. Thus, as to biological 

 conditions, down to my own time the argument derived 

 from Malthus was supposed to present an insuperable 

 difficulty. Whatever the temporary advance of comfort, 

 it would be swamped for the masses by the increase of 

 population, and every social reform resting on a deepened 

 sense of unity and a more generous impulse of mutual aid 

 would only defeat itself the more rapidly by the impetus 

 that it would give to the multiplication of devouring 

 mouths. This line of argument, which for three genera- 

 tions served as an intellectual stronghold of obstruction, 

 has crumbled before the actual fall of the birth-rate, as a 

 result of those very improvements which were to flood the 

 world with hungry children. The boot is now on the 

 other foot, and the pessimists have to harp on the possibility 

 of race suicide. As to the pessimism of physical science, 

 recent discovery has taught another valuable lesson. The 

 speculations of Lord Kelvin, deriving an appearance of 

 demonstrative cogency from their mathematical form, led 

 men to conceive the earth as relatively short lived, and the 

 present age as a late stage of its existence. In vain men 

 like Tluxley pointed out that the entire cogency of Lord 

 Kelvin's reasoning was in the method of deducing con- 

 clusions from its assumptions, that these assumptions were 

 unverified, that they were valid only if our knowledge of 



