34 COSMIC PHILOSOPHY. [pt. l 



less developed sciences. The sciences which have arrived 

 at the highest perfection are those which have carried quan- 

 titative prevision to the farthest extent. Between astronomy, 

 which can foretell the precise moment at which a solar 

 eclipse will begin a hundred thousand years hence, and 

 meteorology, which cannot surely foretell from week to week 

 the state of the weather, there is an almost immeasurable 

 difference in scientific completeness. The chemist can pre- 

 dict the exact quantity of effect which will be produced by 

 mingling a new substance with any given compound, the 

 properties of which have been studied ; while the physio- 

 logist cannot surely predict the exact amount of effect which 

 will be produced by a drug that is introduced into the 

 organism; and we accordingly consider chemistry a much 

 more advanced science than physiology. And lastly, let us 

 note that the date which we habitually assign for the com- 

 mencement of any science is the date at which its previsions 

 began to assume a definitely quantitative character. Dyna- 

 mics is said to have become a science when Galileo deter- 

 mined the increment of velocity of falling bodies. Chemistry 

 became a science when Lavoisier, De Morveau, and Dalton 

 discovered the exact proportions in which the most im- 

 portant chemical combinations take place. No science of 

 heat was possible until the invention of the thermometer 

 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 number 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 science and 

 ordinary knowledge consists in the greater remoteness of the 



