COSMIC PHILOSOPHY 



mometer enabled men to measure the degrees 

 of temperature. There was no science of optics 

 until it had been ascertained that the sines of 

 the angles of incidence and reflection or refrac- 

 tion bear to each other a constant ratio. And 

 with Mr. Joule's discovery that a certain num- 

 ber of degrees of heat is equivalent to a certain 

 amount of mechanical motion, there becomes 

 possible a science of thermodynamics which shall 

 express by a single set of formulas the activities 

 of forces hitherto treated as generically different. 

 The second difference of degree between sci- 

 ence and ordinary knowledge consists in the 

 greater remoteness of the relations of likeness 

 and unlikeness which science detects and clas- 

 sifies. The child who, when an orange is pre- 

 sented to him, infers that on sucking it he shall 

 experience a pleasant taste ; the savage who, 

 finding the half-eaten carcass of a sheep, con- 

 cludes that a lion has been in the neighbour- 

 hood ; and Leverrier, who, noticing that the 

 observed motions of Uranus do not coincide 

 with its motions as predicted, suspects the ex- 

 istence of a still remoter planet which disturbs 

 it — go, all of them, through what is essentially 

 the same process. The child has mentally 

 grouped together the attributes of an orange; 

 and when certain members of the group — as 

 the shape and colour — are afterwards presented 

 to his consciousness, there occurs a mental re- 



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