Edward Gibbon,
History of the Decline and Fall of the Roman Empire…
“ The valor of Diocletian was never found inadequate to his duty, or to the occasion; but he appears not to have possessed the daring and generous spirit of a hero, who courts danger and fame, disdains artifice, and boldly challenges the allegiance of his equals. His abilities were useful rather than splendid; a vigorous mind, improved by the experience and study of mankind; dexterity and application in business; a judicious mixture of liberality and economy, of mildness and rigor; profound dissimulation, under the disguise of military frankness; steadiness to pursue his ends ”
