Mentat- Aspects oe Ageing 47 



evident that this has no single source, but de})ends on })sycho- 

 logical constitution, and social and cultural influences. 

 Moreover it is not indifferently eni^aned in conipensatin<i for 

 any and every defect l)ut varies oreatly in the same individual 

 in respect of different achievements and ways of substitutive 

 attainment. To foretell its effectiveness in a senescent we 

 should need to know how it had worked in the past, and upon 

 what intact resources it could now draw. As Piaget found at 

 the other end of life, reorganisation, even wdien unforeseen 

 and sudden, never occurs unless the mental combination 

 which determines it has been prepared by earlier experience. 

 This analogy with the developmental phase may go deeper: 

 adjustment to the problems created by differential increase 

 in abilities may set the pattern that will be followed when the 

 problems are set by differential decline. But of course in facing 

 the latter the individual is hampered, or helped, by the habits 

 he has developed during many decades and the social insti- 

 tutions within which he has exercised his abilities and set up 

 his standards of achievement. David Riesman recently stated 

 in vivid language the predicament of the ageing person who 

 has, in a busy career, confined his activities to ever-renewed 

 tasks given by his environment; or who has given up the 

 struggle early in life and depended heavily on personal and 

 occupational supports which are withdrawn when he retires, 

 leaving him empty of purpose and interests. 



The emphasis in much recent literature about the troubles 

 of the elderly has been upon the restrictions set by their 

 social and cultural environment, which may deny them pres- 

 tige and authority, or accord them security only at the price of 

 loneliness and inactivity. With these must be reckoned the 

 social pressures that may have operated over a long preceding 

 stretch of time to unfit them for the chanoes inevitable in 

 later life. 



For the study of these and of most other mental aspects of 

 ageing, investigations prolonged enough to survey the changes 

 in individuals over many years are essential. 



