14 Habit means that function 



our own case we get a good deal of insight 

 into this process in what we can observe of 

 the growth of habit. What was originally 

 acquired by a long series of trials and 

 failures, engrossing all our attention, becomes 

 at length "secondarily automatic" — to use 

 Hartley's now classic phrase. Of this such 

 feats as skating or piano-playing are familiar 

 examples. This mechanization of habit is 

 aptly described in the saying that "use is 

 second nature." It sets attention free for 

 new advances which would else be impossible. 

 So natura naturata is the condition of further 

 natura naturans. The organism gives us a 

 warrant for the term " mechanization " in the 

 permanent modification of brain and muscle 

 which the acquisition of new dexterities en- 

 tails ; and mutatis mutandis, the same holds 

 true of the knowledge we know so thoroughly 

 that, as Samuel Butler said, we have ceased 



