INTELLECTUAL EVOLUTION 323 



step by step initiated, and are told to call each machine as we 

 are introduced to it by the name of a rule. If, as is possible, 

 we are told that no rule is wanted and that we have " merely 

 to think," this only means that we have already learnt the use 

 of the machine required and that we have now to apply it under 

 slightly different circumstances. In other words, we have to be, 

 in a mild way, original. 



But I have not yet mentioned what is, perhaps, the most 

 remarkable characteristic of such pieces of mechanism. The 

 understanding of one makes the understanding of another possible. 

 You cannot find a lowest common multiple, unless you have 

 first learnt the art of division. You cannot attack algebra 

 with success unless you have made some headway with arith- 

 metic : it is foolish to begin trigonometry without some know- 

 ledge of geometry. The man, therefore, who finds a particular 

 piece of mechanism very difficult to understand cannot advance 

 to the study of other pieces of mechanism, the understanding 

 of which is impossible while the one that has defeated him 

 remains unmastered. And yet, perhaps, more advanced machines 

 are not much more puzzling, in some cases possibly not at all 

 more puzzling, than the one which proved insurmountable. 

 But the stupid man, thus nonplussed, is at the end of his 

 tether. The clever man gets over the difficulty and finds at 

 his disposal a number of other machines, from the use of which 

 the stupid man is debarred. Turning these to good account, 

 he advances into new worlds of thought, while the man who 

 started to race with him no longer even limps behind, but has 

 put on his coat and looked out for some humbler occupation. 

 All this may possibly be made clearer by a simple illustration. 

 Imagine two men one of whom can walk five and the other four 

 miles an hour. And imagine that the power to walk five miles 

 an hour admits to the use of a bicycle, by the aid of which 

 fifteen may be covered in the same time. The difference be- 

 tween the two is no longer one but eleven miles. And further 

 suppose that to the man who can ride fifteen miles an hour on a 

 bicycle is permitted the use of some other machine railway 

 train or flying machine from which the mere pedestrian is 



