A Treatise on Painting/Chapter 150
Chap. CL.—The Character of Figures in Composition.
In general, the painter ought to introduce very few old men, in the ordinary course of historical subjects, and those few separated from young people; because old people are few, and their habits do not agree with those of youth. Where there is no conformity of custom, there can be no intimacy, and, without it, a company is soon separated. But if the subject require an appearance of gravity, a meeting on important business, as a council, for instance, let there be few young men introduced, for youth willingly avoids such meetings.