40 Aubrey Lewis 



and Falstaff at seventy-nine: Humboldt wrote the five 

 volumes of his Kosmos between the ages of seventy-six and 

 eighty-nine: Goethe composed the second part of Faust 

 between seventy and eighty: Galileo at seventy-four, Euler at 

 seventy-two, Laplace at seventy-five were still making valuable 

 original contributions; and there are many others. It was, 

 however, in the continuation of work which had occupied their 

 youth or their prime that these old men were engaged, and as 

 Lehman points out, they chiefly assembled knowledge or 

 completed an edifice they had been building all their lives. 

 But although qualities of the highest order, such as are 

 essential for great scientific discoveries and the creation of 

 literary and musical works of genius, decline with advancing 

 years, many of the requisites for distinguished work have 

 clearly been retained. It is not yet possible to define or to 

 measure these qualities, to which we give loose names such 

 as mental energy, or determination. But, as Terman has 

 suggested, it is desirable that as full medical and psychological 

 observations as possible should be made of "contrasting 

 groups of creative persons, including (a) individuals whose 

 productivity declined early and rapidly and (b) others who 

 have remained productive to a much later age. Such con- 

 trasting groups can be found in the faculty of any large 

 University. An important feature of the clinical approach 

 would be the study of motivation in the individual and how 

 these are affected both by specific influences of the immediate 

 environment and by the large social and cultural trends 

 characteristic of the given time and place". The effort of the 

 Guilford group at the University of Southern California to 

 develop tests of "creative thinking" may permit psychometric 

 estimates more relevant to the contrast than existing intelli- 

 gence tests. 



Other measurements have been made, notably of memory, 

 but these have not added much to the common observation 

 that memory declines with advancing years, that individuals 

 differ widely in this respect, and that in the same individual 

 the amount of decline varies with the sort of material learned 



