Because his subject was deceased, Trumbull used for his model Mercer's son Hugh Jr.; he twice sketched the young man in Fredericksburg, Virginia, in April 1791.
General Hugh Mercer, Jr., 1791
Jefferson biographers express astonishment that the apprenticeship with Wythe lasted five full years, 1762 - 67, at a time when almost no one studied law for more than two. Patrick Henry studied
not more than six weeks, or so at least he told Jefferson, and Wythe for one was so convinced of the inadequacy of Henry’s training he refused to sign his license. Jefferson’s years under Wythe, years of virtually uninterrupted reading, not only in the law but also in ancient classics, English literature, and general political philosophy, were not so much an apprenticeship for law as an apprenticeship for greatness.