690 



SCIENCE 



[N. S. Vol. XL. No. 1037 



the latter the individual selects the stimuli 

 which are to make permanent impressions. 

 An important function in the accomplishment 

 of this purpose is the rejection of stimuli be- 

 lieved to be unimportant or harmful, and seiz- 

 ing upon and fixing of those recognized as of 

 greatest value. In this selection lies the path- 

 way to wisdom. It determines the ideals of 

 the individual. It shapes the ego and sets the 

 lines of future development. The memory- 

 pictures photographed in the highly labile 

 molecules of the brain constitute a record of 

 all our available knowledge, not only that 

 gained through personal experience, but that 

 acquired from any source. "We rehear the 

 spoken and reread the written word. We re- 

 call the facts of history. We utilize without 

 conscious effort in our daily dealings the 

 mathematical skill acquired in childhood. We 

 make practical application of the scientific 

 discoveries of the past in supplying our- 

 selves with the necessities and comforts of 

 life. We enjoy the literature of all nations in 

 all ages. In short, the storehouses of learning 

 to which we have access are practically limit- 

 less in their wealth, and from this we may se- 

 lect at will and appropriate to our own use 

 without diminishing to the smallest degree 

 what is left for others. 



In order to be of greatest service, memory 

 pictures must be clear and properly placed. 

 Clearness and association are essential to 

 prompt recall and correct recognition. 

 Memory, like all other functions of the nerv- 

 ous mechanism, is capable of improvement 

 by exercise. When memory pictures have a 

 faulty setting, they may influence behavior 

 disastrously. The old man thinks all this talk 

 about impure milk killing infants and in- 

 fected water causing typhoid fever is non- 

 sense, because all his life people, both young 

 and old, have been drinking dirty milk and 

 polluted water. He does not know or recog- 

 nize the fact that many even within his own 

 circle have died from these causes. In his ex- 

 perience these facts have not been recognized 

 as possessing any causal relationship. Half his 

 children have died from the summer diarrheas 

 of infancy and others have died in youth 



from typhoid, but he has always connected 

 these bereavements with the world-old belief 

 that disease could not be prevented nor death 

 delayed. The failure to properly correlate ex- 

 periences or their memory pictures is one of 

 the things which prevent many elderly peo- 

 ple, especially the untrained, from adjusting 

 themselves to advances in knowledge. Many 

 superstitious rites and ceremonies have their 

 origin in the faulty conception of cause and 

 effect. Many reason post hoc ergo propter 

 hoc. This faulty logic is still a strong sup- 

 port of charlatanism in its many survival 

 forms. 



The study of the structure and function of 

 the nervous mechanism makes plain what 

 should be attempted in securing an education. 

 We have seen that in the acquisition of knowl- 

 edge pathways to the cerebral cortex must be 

 opened up. Conduction of nervous impulses 

 meets with resistance as it passes from one 

 neuron to the next. This resistance grows 

 less with each traverse of the impulse along 

 the same path, and with frequent repetition 

 the trail becomes so smooth that impulses pass 

 through without conscious effort. It is easier 

 to open up pathways to the cortex in youth 

 than in later years because the lability and 

 plasticity of the nervous tissue decrease with 

 advancing age. However, lines of conduction 

 established in the plastic period are never ob- 

 literated save by disease or death. Even with 

 approaching senility, when the opening of new 

 lines is impossible, those established in youth 

 continue to operate. Truly, learning becomes 

 the solace of age. The educated octogenarian 

 remains in sympathy and intelligent touch 

 with the outer world, while his untrained 

 brother finds himself isolated and marooned 

 on a small barren island. Furthermore, it 

 has been demonstrated that the lines of con- 

 duction which serve in one department of 

 learning are useless in the conduction of in- 

 formation from other sources. The acquisi- 

 tion of mathematical skill does not give spe- 

 cial preparation for historical erudition. 

 These elemental psychological facts indicate 

 that in youth training of the nervous systemi 

 should be broad, the purpose being to estab- 



