402 THE EVOLUTION OF MEMORY 



or king, he develops just such dexterities in thought and action as 

 are necessary to him, but is burdened with no more. Our human 

 memory ', our power of growing mentally in response to the stimulus 

 of use and experience is a device by means of which nature has 

 surmounted the difficulty of evolving an untold number of reflexes 

 and instincts. Each real reflex and instinct demands for its 

 evolution and maintenance a separate process of selection. For 

 example, the reflexes of the heart and the bowels, and the instincts 

 of hunger and sexual love are entirely separate things not evolved 

 by the same process of selection and not equally well developed 

 in every individual. If the individual is defective in any important 

 reflex or instinct, he leaves no offspring. Therefore nature must 

 maintain all. When they are very numerous, individuals defective 

 in one or another are so many that the death-rate tends to exceed 

 the birth-rate. Therefore there is a limit to their number. In 

 other words there is a limit to the complexity of the individual in 

 innate characters, and therefore a limit to the number of innate 

 reactions he is able to make to the environment. On the other 

 hand in memory nature evolves and maintains only one thing. 

 But that one thing, as I say, is capable of supplying any number 

 of emotions and automatic reactions which answer precisely the 

 same purpose as innate reactions. 



664. It is a principal business of our lives to acquire these 

 dexterities in performance (e.g. walking), these imitation reflexes 

 (e.g. quick withdrawal from a cause of pain) and these imitation 

 instincts (e.g. patriotism). But, though a great advantage is gained 

 when the acquirements are made, one almost as great is lost. We 

 then think and act more quickly in familiar situations. When the 

 adult stage is reached we are by virtue of them as fit or more fit 

 than an insect to face the battle of life. But each important ac- 

 quirement is written, as it were, in indelible ink on the sheet of the 

 mind. This matters comparatively little in the case of those 

 automatic actions which take the place of reflexes. They are 

 almost always useful, as for example, the automatic co-ordinations 

 of our muscles by means of which we walk, speak, cycle, swim, knit, 

 or dodge blows. But our bad as well as our good acquirements 

 are imitation instincts. Once acquired, they tend perpetually to 

 pull us down. Moreover, as we grow older, we tend to lose our 

 splendid human capacity for learning. Old habits, good or bad, 

 persist ; new habits cannot easily be acquired. 



665. In addition to the acquired dexterities and mental 

 attitudes which depend on records unconsciously retained, our 



