The English political philosopher and publicist James Harrington was the eldest son of Sir Sapcote Harrington, of Rand, Lincolnshire. As such, he belonged to a junior branch of a family that had been prominent from the days of Richard I. An erudite man, Harrington must have acquired his great knowledge of languages, literature, and history largely independently, since he spent only two or three years at Oxford and in the Middle Temple and took no degree. During the 1630s he traveled extensively on the Continent and served in an English volunteer regiment in the forces of one of the palatine electors. From these experiences, and especially from a visit to Venice, he gathered much of the data that later formed the raw material for his political theory.

When civil war broke out in England, Harrington took a neutral position, despite his republican sympathies, because...