72 GENERAL VIEW AND BASIS OF SCIENTIFIC RESEARCH. 



The action of the memory is not only automatic, but 

 ften unconscious. Multitudes of past experiences and 

 impressions continually arise into our mental vision with- 

 out our experiencing any conscious exertion. The act of 

 associative suggestion of ideas is sometimes attended by 

 consciousness and sometimes not; it is only when the 

 ideational action is sufficiently strong, and we direct our 

 observing powers upon it, that we become conscious of it. 

 There is cogent evidence for believing that, during our, 

 waking state, precisely similar trains of mental action 

 occur in our brain when we do not observe them, as when 

 we do ; just as many of our muscular actions are both 

 automatic and unobserved by us. 



All these remarks respecting the memory show the 

 importance of that faculty, and therefore the importance 

 of educating it. ' It is said that Sir Isaac Newton, at one 

 period of his life, entirely forgot the contents of his cele- 

 brated " Principia," in consequence of his neglecting to 

 exercise the memory.' 1 c It is a fact well attested by experi- 

 ence, that the memory may be seriously injured by pressing 

 upon it too hardly and continuously in early life ; ' but, ' a 

 regular exercise short of fatigue is improving to it.' 2 The 

 most valuable way of improving the memory for scientific 

 purposes is by systematic study and experience of science, 

 and especially an orderly classification and arrangement of 

 ideas in accordance with the great principles and relations 

 of nature; an empirical classification or arrangement is 

 much less effectual. There is a limit to the number of 

 ideas which the human mind can contain, and new ideas 

 more readily obliterate the impressions of old ones, unless 

 the latter are associated with many others by a strong bond 



1 Winslow, Obscure Diseases of the Brain and Mind, p. 680. 



2 Sir Henry Holland's Mental Pathology. 



