SECTION 22 OBSERVATION. 281 



in any country customs other than their own. One remembers 

 in this connection Mark Twain's genial Negro who could not 

 comprehend why the French people did not speak English. 

 The molecular movements of objects at rest or in the growth 

 of animate beings remain for this reason commonly unnoticed, 

 just as at first the isomeric aspects of compounds escape atten- 

 tion; we ignore the fact that a "given mass weighs slightly 

 less, and falls to the ground a little less rapidly, in the tropics 

 than elsewhere" (F. Soddy, op. cit., p. 25), or that the require- 

 ments of children often seriously differ from those of adults, 

 or that a remedy efficacious at one stage, or in one affection, 

 may be useless or even detrimental at an earlier or later stage, 

 or in another affection; and the influence of vast periods, as 

 in the formation of mountains, rivers, or land, or in the evolu- 

 tion of living forms or even of chemical elements, or in the 

 development of human institutions and human culture, demand 

 measurement, whilst in theoretical and practical problems, the 

 near and distant future equally require to be taken into account. 

 "At the time of Alexander's invasion a good part of the now 

 arid desert consisted of populous towns and prosperous villages. 

 So also, the jungle now known as the Sunderbun, and inhabited 

 by tigers and other wild beasts, was, a few centuries ago, the 

 seat of a flourishing kingdom." (Banerjea, op. cit., p. 8.) And 

 time sees important changes induced by man's interposition. 

 "The worst land can be converted into the most fertile by the 

 application of proper manures and the adoption of a well- 

 regulated method of agriculture. . . . Afforestation may lead to 

 an increase in rainfall where it is at present scanty, and irriga- 

 tion may be so practised as to carry water to any place where 

 it is wanted." (Ibid., p. 26.) What more wonderful substance 

 is there in nature than water? Now it is a transparent liquid 

 evaporating in almost any degree of temperature, saturating 

 the atmosphere, forming steam and clouds, descending from 

 the sky as rain, snow, sleet, and hail, appearing as sparkling 

 dew and lacy frost, turning into solid ice, splitting the rocks 

 because of its unique quality of expanding just anterior to 

 solidifying, and entering largely into the composition of living 

 forms. Sufficient has been adduced to show the need of always 

 calculating on the possibility that objects and their environment 

 do not possess that uniformity which they momentarily and in 

 certain localities appear to present. 



"There rolls the deep where grew the tree. 



earth, what changes hast thou seen! 



There where the long street roars, hath been 

 The stillness of the central sea. 



The hills are shadows, and they flow 



From form to form, and nothing stands; 



They melt like mist, the solid lands, 

 Like clouds they shape themselves and go." 



(Tennyson, In Memoriam, cxxiii.) 



