XI PHENOMENA OF ORGANIC NATURE 371 



outside and on the window-sill, opened the window, 

 got into the room, and stole your tea-pot and 

 spoons. You have now arrived at a vera causa ; 

 you have assumed a cause which, it is plain, is 

 competent to produce all the phenomena you have 

 observed. You can explain all these phenomena 

 only by the hypothesis of a thief. But that is a 

 hypothetical conclusion, of the justice of which 

 you have no absolute proof at all ; it is only 

 rendered highly probable by a series of inductive 

 and deductive reasonings. 



I suppose your first action, assuming that you 

 are a man of ordinary common sense, and that 

 you have established this hypothesis to your own 

 satisfaction, will very likely be to go off for the 

 police, and set them on the track of the burglar, 

 with the view to the recovery of your property. 

 But just as you are starting with this object, some 

 person comes in, and on learning what you are 

 about, says, " My good friend, you are going on a 

 great deal too fast. How do you know that the 

 man who really made the marks took the spoons ? 

 It might have been a monkey that took them, and 

 the man may have merely looked in afterwards." 

 You would probably reply, " Well, that is all very 

 well, but you see it is contrary to all experience 

 of the way tea-pots and spoons are abstracted ; so 

 that, at any rate, your hypothesis is less probable 

 than mine." While you are talking the thing 

 over in this way, another friend arrives, one of 



