60 SCIENCE OF THE COSMOS. 



we have been able to discover in some the empire of laws, grand 

 and simple as Nature herself. Doubtless, the bounds of 

 this empire will be enlarged as the physical sciences gradually 

 enlarge their domain, and become more perfect. Brilliant 

 examples of such progress have appeared in our own times, in 

 the phsenomena of electro-magnetism, and in those of the 

 propagation of luminous waves and of radiant heat. The 

 doctrine of evolution shows us how, in organic development, 

 all that is formed is sketched out as it were beforehand, and 

 how the tissues of both vegetable and animal matter are 

 uniformly produced by the multiplication and transformation 

 of cells. 



The generalisation of laws which were first applied to 

 smaller groups of phsenomena advances by successive grada- 

 tions, and their empire is extended, and their evidence 

 strengthened, so long as the reasoning process is directed to 

 really analogous phsenomena. But as soon as dynamic views 

 no longer suffice, and the specific properties of heteroge- 

 neous matter come into play, fear may be entertained 

 lest, in the too obstinate pursuit of laws, we may arrive at 

 impassable chasms : the principle of unity fails, and the 

 guiding clue breaks, when, in tracing the effects of natural 

 forces, we come to specific kinds of action. The law ol 

 equivalents, and of definite numerical proportions in com- 

 pound substances, so happily recognised by modern chemists 

 and proclaimed under the antique form of atomic symbols, 

 remains hitherto isolated, and unsubjected to the mathema- 

 tical laws of motion and gravitation. 



Natural productions, which are objects of direct obser- 

 vation, may be logically distributed in classes, order?, 

 and families, Such distribution does no doubt give greater 



