122 ESSAY ON PROBABILITIES. 



which are compared with A are such as to exhibit what 

 we call accidental fluctuations, we are apt to imagine 

 that the difference between the two sequences is a 

 consequence of A. In the mysterious subject of luck,, 

 already alluded to, this tendency to error produces 

 superstition. There are many who imagine that the 

 change of seats,, or a new pack of cards, changes the 

 luck. They imagine it, because they observe that 

 the luck is not the same before the change as after it, 

 which, for the most part, is true. But it is equally 

 true that, for the most part, no number of games exhi- 

 bits the same fortune as those which precede it ; that 

 is, this change of luck is always taking place, but is 

 usually only perceived when the introduction of some 

 novel circumstance affords a point to date from, on one 

 side and the other. The growth of the superstition is 

 this : An individual who has been unlucky during 

 several games, happens to begin to win after the intro- 

 duction of new cards. His fortune changes, as most 

 probably it will do ; for if the chances be even, and 

 three games have previously been lost, it is seven to one 

 against the next three games resembling them, and an 

 even chance that he shall win the next game. If he 

 win the next, or, indeed, if he do not go on losing, he 

 notes the circumstance, and the next time a run of ill 

 luck occurs, he takes particular care to repeat the expe- 

 riment. In this way he soon furnishes himself with a 

 tolerable number of facts in support of his theory. 

 The exceptions are forgotten ; for it is the character of 

 negative events to lay less firmly hold of the mind* 

 than positive ones. Thus the theory of the change of 

 the weather with that of the moon receives more con- 

 firmation from one fact in its favour than of doubt from 

 two against it. This last notion is another case in 

 point. The weather of any three days, in by far the 

 most instances, differs from that of the preceding three 



* The lucky hit of a prophet of the weather, in foretelling the coldest 

 day of January, 1838, did more to establish his infallibility than weeks of 

 succeeding mistakes could destroy. 



