200 ARISTOCRA C Y AND E VOL UTION 



Book in efficiency of the more efficient pair would, it is 

 perfectly obvious, be due to that blade in respect of 

 which this pair differed from the pair which was less 

 efficient, not to the blade in respect of which 

 both pairs were similar. Again, let us take Mill's 

 case of the two numerals five and six. If five is 

 always to be the number multiplied, and six is 

 always to be the multiplier, it is true we cannot say 

 which does most in producing the result thirty. 

 But if the number to be multiplied remains always 

 five, whilst the multiplying number varies if it is in 

 one case six and in another case ten, and if the result 

 of the multiplication in the second case is not thirty 

 but fifty, it is obvious that the additional twenty 

 which results from our multiplying by ten is due 

 not to any change in the number multiplied, but to 

 the additional four introduced into the number 

 multiplying. To these illustrations we may add two 

 others the movement of a modern bicycle and the 

 movement of a man running. A modern bicycle 

 cannot be propelled without a chain ; and if there 

 were only one kind of bicycle, in the world, Mill 

 might fairly have said that it was meaningless 

 and useless to ask whether the wheels or the chain 

 contributed most to its velocity. But if there are 

 two bicycles, with precisely similar wheels, but with 

 dissimilar chains, and if the same man riding on one 

 can accomplish ten miles an hour only, but on the 

 other fifteen, the common sense of every bicycle 

 rider in the world will tell him that the additional 

 five miles are contributed entirely by the chain, and 



