306 INDUCTION. 



the solubility of substances in one another, depends* (at least in some 

 degree) on the similarity of their elements. 



An empirical law, then, is an observed unifonnity, presumed to be 

 resolvable into simpler laws, but not yet resolved into them. The as- 

 certainment of the empirical laws of phenomena, often precedes by a 

 long interval the explanation of those laws by the Deductive Method : 

 and the verification of a deduction usually consists in the comparison 

 of its results with empirical laws previously ascertained. 



§ 2. From a limited number of ultimate laws of causation, there are 

 necessarily generated a vast number of derivative unifonnities, both 

 of succession and of coexistence. Some are laws of succession or of 

 coexistence between different effects of the same cause : of these we 

 had abundant examples in the last chapter. Some are laws of suc- 

 cession between effects and their remote causes ; resolvable into the 

 laws which connect each with the intermediate link. Thirdly, when 

 causes act together and compound their effects, the laws of those 

 causes generate the fundamental law of the eftect, namely, that it de- 

 pends upon the coexistence of those causes. And, finally, the ordei 

 of succession or of coexistence which obtains among effects, necessa- 

 rily depends upon their causes. If they are effects of the same cause, 

 it depends upon the laws of that cause ; if of different causes, it de- 

 pends upon the laws of those causes severally, and upon the circum- 

 stances which determine their coexistence. If we inquire further when 

 and how the causes will coexist, that, again, depends upon their causes : 

 and we may thus trace back the phenomena highei* and higher, until 

 the different series of effects meet in a point, and the whole is shown 

 to have depended ultimately upon some common cause ; or until, in- 

 stead of converging to one point, they terminate in different points, 

 and the order of the effects is proved to have arisen fr-om the original 

 collocation of some of the primeval causes, or natural agents. For 

 example, the order of succession and of coexistence among the 

 heavenly motions, which is expressed by Kepler's laws, is derived 

 from the coex'istence of two primeval causes, the sun, and the original 

 impulse or projectile force impressed upon each planet.t Kepler's 

 laws are resolved into the laws of these causes and the fact of their 

 coexistence. 



Derivative laws, therefore, do not depend solely upon the ultimate 

 laws into which they are resolvable : they mostly depend upon those 

 ultimate laws and an ultimate fact ; namely, the mode of coexistence 

 of some of the original elements of the universe. The ultimate laws 

 of causation might be the same as at present, and yet the derivative 

 laws completely different, if the causes coexisted in different propor- 

 tions, or with any difference in those of their relations by which the 

 effects are influenced. If, for example, the sun's attraction, and the 



* Thus, water, of which eight-ninths in weight are oxygen, dissolves most bodies which 

 contain a high proportion of oxygen, such as all the nitrates, (which have more oxygen 

 than any others of the common salts,) most of the sulphates, many of the carbonates. &c. 

 Again, bodies largely composed of combustible elements, like hydrogen and carbon, are 

 soluble in bodies of similar composition ; rosin, for instance, will dissolve in alcohol, tar in 

 oil of turpentine. This empirical generalization is far from being universally true ; no 

 doubt because it is a remote, and therefore easily defeated, result of general laws too deep 

 for us at present to penetrate : but it will probably in time suggest processes of inquiry, 

 leading to the discovery of these laws. 



+ Or (according to Laplace's theory) the sun, and the sun's rotation. 



