412 INDUCTION. 



It is evident, that from a limited number of un- 

 conditional sequences, there will result. a much greater 

 number of conditional ones. Certain causes being 

 given, that is, certain antecedents which are uncon- 

 ditionally followed by certain consequents ; the mere 

 coexistence of these causes will give rise to an unli- 

 mited number of additional uniformities. If two 

 causes exist together, the effects of both will exist 

 together ; and if many causes coexist, these causes (by 

 what we shall term hereafter, the intermixture of their 

 laws) will give rise to new effects, accompanying or 

 succeeding one another in some particular order^ 

 which order will be invariable while the causes con- 

 tinue to coexist, but no longer. The motion of the 

 earth in a given orbit round the sun is a series of 

 changes which follow one another as antecedents and 

 consequents, and will continue to do so while the sun's 

 attraction, and the force with which the earth tends to 

 advance in a direct line through space, continue to 

 coexist in the same quantities as at present. But 

 vary either of these causes, and the unvarying succes- 

 sion of motions would cease to take place. The series 

 of the earth's motions, therefore, though a case of 

 sequence invariable within the limits of human expe- 

 rience, is not a case of causation. It is not uncon- 

 ditional. 



To distinguish these conditionally uniform se- 

 quences from those which are uniform uncondition- 

 ally ; to ascertain whether an apparently invariable 

 antecedent of some consequent is really one of its 

 conditions, or whether, in the absence of that antece- 

 dent, the effect would equally have followed from some 

 other portion of the circumstances which are present 

 whenever it occurs ; is a principal part of the great 



