52 INTRODUCTION TO SCIENCE 



We call them 'Laws of Nature,' and honour 

 them because we find that if we obey them we 

 win something for our pains. The cards are 

 our theories and hypotheses, the tricks our experi- 

 mental verifications." 



PARTICULAR AIMS OF DIFFERENT SCIENCES. 

 It was Kant who said that any branch of 

 knowledge contains just so much science as it 

 contains of mathematics; and this is not very 

 different from saying that all science begins with 

 measurement. If this view is pressed it leads to 

 the conclusion that the only perfect science is 

 mechanics, and that the only quite precise sciences 

 are those dealing with processes which can be 

 analysed into the motions of ideal corpuscles. 



This seems to us an impracticable ideal of 

 precision, for it must be noted that facts whose 

 mechanical analysis is not within sight need not 

 on that account be treated unscientifically. 

 They may be measured, though not with the 

 same measure as is used for the stars in their 

 courses. Complex as are the inborn variations 

 of plants and animals, they can be treated by 

 the same statistical methods as are used in 

 recording the simple phenomena observed when 

 dice are thrown ten thousand times. Myste- 

 rious as are the facts of inheritance, the expert 

 can occasionally prophesy safely as to the nature 

 of the chicks which will emerge from an unhatched 



