30 PLEASANT WAYS IN SCIENCE. 



external to the earth whose varying aspect or condition can 

 inform us beforehand of changes which the weather is to 

 undergo, the sun is that body. That for countless ages the 

 moon should have been regarded as the great weather- 

 breeder, shows only how prone men are to recognize in 

 apparent changes the true cause of real changes, and how 

 slight the evidence is on which they will base laws of associa- 

 tion which have no real foundation in fact Every one can 

 see when the moon is full, or horned, or gibbous, or half-full ; 

 when her horns are directed upwards, or downwards, or 

 sideways. And as the weather is always changing, even 

 as the moon is always changing, it must needs happen that 

 from time to time changes of weather so closely follow 

 changes of the moon as to suggest that the two orders of 

 change stand to each other in the relation of cause and 

 effect Thus rough rules (such as those which Aratus has 

 handed down to us) came to be formed, and as (to use 

 Bacon's expression) men mark when such rules hit, and 

 never mark when they miss, a system of weather lore 

 gradually comes into being, which, while in one sense based 

 on facts, has not in reality a particle of true evidence in its 

 favour every single fact noted for each relation having 

 been contradicted by several unnoted facts opposed to the 

 relation. There could be no more instructive illustration of 

 men's habits in such matters than the system of lunar 

 weather wisdom in vogue to this day among seamen, though 

 long since utterly disproved by science. But let it be re- 

 marked in passing, that in leaving the moon, which has no 

 direct influence, and scarcely any indirect influence, on the 

 weather, for the sun, which is all-powerful, we have not got 

 rid of the mental habits which led men so far astray in 

 former times. We shall have to be specially careful lest it 

 lead us astray yet once more, perhaps all the more readily 

 because of the confidence with which we feel that, at the 

 outset anyway, we are on the right road. 



I suppose there must have been a time when men were 

 not altogether certain whether the varying apparent path of 



