INTRO D UCTOR Y 1 3 



I do not here express an opinion, they must know the order 

 of nature to which they respond, and in that case the seed on 

 the wheel would seem to be not only misled but deceived, exactly 

 as a brood of chicks seems to us to be deceived by an imitation 

 of the call of the mother hen; but the essential point is that, 

 whether they know it or not, the changes in living things which 

 are directly due to nature are beneficial only so far as the condi- 

 tions of their life are, on the average, essentially like those in 

 which the lives of their ancestors were passed. 



Now the order, of nature presents infinite diversity : the differ- 

 ent ways in which events may be combined are innumerable ; and 

 no natural response can be judicious or beneficial under all cir- 

 cumstances. We accordingly find, in all the living things we 

 know best, and are most intimately concerned with, a wonderful 

 provision of their nature, by means of which those of their actions 

 which are most apt to mislead are improved and perfected and 

 developed by normal use, so that we are no longer able to tell 

 what they will do from knowledge of their nature alone, since 

 their actions are in part dependent on their training and expe- 

 rience, and on their individual contact with the world. 



The question whether capacity for improvement through con- 

 tact with the world is natural or not is much easier to ask than 

 to answer. Are the benefits that attend training and education 

 and experience part of the nature of living things, or do they add 

 to nature something it did not before contain ? Is knowledge of 

 the world around us part of our nature, or does it add something 

 new on to our nature ? If it is natural, do we simply find or dis- 

 cover our nature, or do we make it or any part of it ourselves ? 

 Any answer we try to give is attended with difficulties. If living 

 things make any part of their nature, the word must mean much 

 more than is recognized in common usage ; and yet the assertion 

 that knowledge and experience and training add nothing to 'the 

 nature of living beings is beset by difficulties which at first sight 

 seem equally grave. 



In some cases we can show that improvement by training is 

 no more than might have been expected, for we can imitate it 

 by means of stimuli which have nothing in common with the 

 natural stimuli except the manner of their application. Normal 



