OF THE THEORY OF PROBABILITIES. 607 



is analogous to the infinite and infinitely smooth horizontal plane, which would enable us to 

 verify the first law of motion. 



(3) The simple negative notion of the absence of disturbing forces is perpetually con- 

 founded with that of a tendency inherent in a series of successively developed results to restore 

 the balance of frequency of occurrence, when this has been by accidental circumstances tem- 

 porarily deranged. It is commonly thought that this notion, which, as we know, is the founda- 

 tion of many unsuccessful attempts to circumvent fortune, is sufficiently refuted by saying, that 

 what is past can exert no influence on what is yet to come. But in reality the past influences 

 the future in a thousand different ways ; and it is only in idea that we can secure the possibility 

 of an indefinite series of trials, of which those which we regard as the permanent circumstances 

 are not progressively, however slowly, undergoing alteration. The dice box for example wears 

 smooth, and the edges of the die are rounded ; and though, in this example, we cannot say what 

 result is facilitated by the change, yet this is not always the case. Such progressive altera- 

 tions may tend so to alter the ratio of frequency of occurrence, as to restore the balance which 

 the result of past trials has disturbed. There is thus nothing absurd in the notion of a restora- 

 tive and balancing tendency, though the grounds on which it is commonly assumed indicate 

 much confusion of thought. It would for instance be perfectly reasonable to inquire, whether 

 in the succession of seasons hot years are not oftener followed by cold and cold by hot, than 

 vice versa. Such questions indicate a branch of the theory of methods of observation to 

 which hitherto but little attention has been paid. 



Vol. IX. Part IV. 78 



