An Introduction to a Biology 



ently difficult, the difficulty resulting from the extreme 

 difference of the two points of view. A midge walking 

 across a picture of a meadow done by the three-colour pro- 

 cess would assert that it was traversing a white plain, over 

 which were distributed patches of different sizes and three 

 colours red, blue, and yellow ; a child would maintain 

 that it was walking across a picture of a field ; each would 

 be convinced that he was right and the other wrong ; yet 

 that both were right could be recognised by any man able 

 to use a magnifying lens. This leads us to a third feature 

 of the relation between our two classes (which results from 

 the fact that our knowledge has probably developed along 

 those lines that our point of view has made most valuable), 

 namely, that in proportion as our knowledge of the com- 

 ponent units is small so is our knowledge of the mass result 

 great. 



To take an example of these two ways of looking at 

 things. The climate of a country or of a long period of time 

 is a mass-phenomenon ; the particular climatic condition 

 of a certain day is referred to as the weather. 1 It is, though 

 it may be becoming less, impossible to predict the weather 

 with precision ; but the nature of the climate of a given 

 country or long period of time is a matter of tolerable cer- 

 tainty. Yet the statement that the summer is warm does 

 not exclude the possibility of a frost in May. That our 

 practical knowledge of the elements is confined to the 

 climate is evident from the fact that, having procured, we 

 begin to put on warmer clothing at a certain period of the 

 year ; but if our intelligence were so sharpened, or our 

 meteorological instruments so improved that we could pre- 



1 " By climate we mean the sum total of the meteorological phenomena 

 that characterise the average condition of the atmosphere at any one place 

 on the earth's surface. That which we call weather is only one phase in 

 the succession of phenomena whose complete cycle, recurring with greater 

 or less uniformity every year, constitutes the climate of any locality." 

 P. 1. J. Hann's " Handbook of Climatology," transl. by E. de C. Ward, 

 1903 



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