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Dorland's investigations into the period of the acme of mental activity, as shown by the records of 400 famous men of modern times, were occasioned by a conversation regarding the increasing American tendency "of relegating the older and middle-aged men to the oblivion of 'innocuous desuetude,' in order that the more progressive and aggressive young men might be given a clear track in the rush to the front." The inquiry is full of interest and perhaps, for many of us, also of surprises. Dividing men into two groups—the workers and thinkers, corresponding, respectively, to the synthetic and analytic types of mind—Dorland investigates the following questions: At what age did a given individual begin to show evidence of mental activity along lines of original research? When did he accomplish the greatest work of his life? How long did his mind continue to functionate and produce in the chosen sphere of activity?
The Age of Mental Virility.. JAMA. 1908;LI(21):1797. doi:10.1001/jama.1908.02540210053017