68 Origin, or Process of Causation of the Series. [CHAP. ill. 



diate products of man s mind, so far indeed as we can make 

 an attempt to obtain them, do not seem to possess this 

 essential characteristic of Probability. Their characteristic 

 seems rather to be, either perfect mathematical accuracy or 

 utter want of it, either law unfailing or mere caprice. If, 

 e.g., we find the trees in a forest growing in straight lines, 

 we unhesitatingly conclude that they were planted by man 

 as they stand. It is true on the other hand, that if we find 

 them not regularly planted, we cannot conclude that they 

 were not planted by man; partly because the planter may 

 have worked without a plan, partly because the subsequent 

 irregularities brought on by nature may have obscured the 

 plan. Practically the mind has to work by the aid of im 

 perfect instruments, and is subjected to many hindrances 

 through various and conflicting agencies, and by these means 

 the work loses its original properties. Suppose, for instance, 

 that a man, instead of producing numerical results by im 

 perfect observations or by the cast of dice, were to select 

 them at first hand for himself by simply thinking of them 

 at once; what sort of series would he obtain? It would be 

 about as difficult to obtain in this way any such series as 

 those appropriate to Probability as it would be to keep his 

 heart or pulse working regularly by direct acts of volition, 

 supposing that he had the requisite control over these organs. 

 But the mere suggestion is absurd. A man must have an 

 object in thinking, he must think according to a rule or for 

 mula; but unless he takes some natural series as a copy, he 

 will never be able to construct one mentally which shall per 

 manently imitate the originals. Or take another product of 

 human efforts, in which the intention can be executed with 

 tolerable success. When any one builds a house, there are 

 many slight disturbing influences at work, such as shrinking 

 of bricks and mortar, settling of foundations, &c. But the 



