SCIENCE.] INTRODUCTORY. " 



always give rise to the same effects. The sun always 

 rises on one side and sets on the other side of the 

 sky ; the changes of the moon follow one another in 

 the same order and with similar intervals ; some stars 

 never sink below the horizon of the place in which 

 we live ; the seasons are more or less regular ; water 

 always flows down-hill; fire always burns; plants 

 grow up from seed and yield seed, from which like 

 plants grow up again; animals are born, grow, reach 

 maturity, and die, age after age, in the same way. 

 Thus the notion of an order of nature and of a 

 fixity in the relation of cause and effect between 

 things gradually entered the minds of men. So far 

 as such order prevailed it was felt that things were 

 explained ; while the things that could not be ex- 

 plained were said to have come about by chance, or 

 to happen by accident. 



But the more carefully nature has been studied, the 

 more widely has order been found to prevail, while 

 what seemed disorder has proved to be nothing but 

 complexity ; until, at present, no one is so foolish as 

 to believe that anything happens by chance, or that 

 there are any real accidents, in the sense of events 

 which have no cause. And if we say that a thing 

 happens by chance, everybody admits that all we 

 really mean is, that we do not know its cause or 

 the reason why that particular thing happens. Chance 

 and accident are only aliases of ignorance. 



At this present moment, as I look out of my window, 

 it is raining and blowing hard, and the branches of the 

 trees are waving wildly to and fro. It may be that a 

 man has taken shelter under one of these trees; perhaps, 

 if a stronger gust than usual comes, a branch will break, 



