The Spirit of Laws is one of the most influential books of all time. This masterpiece of political philosophy was widely read throughout Europe, attracted an especially enthusiastic readership in England, and had a profound effect on the framers of the American Constitution.

Montesquieu (1689-1755), already famous and controversial through his Persian Letters, a work of his youth in which he humorously satirized the foibles of French society, turned in his later years to this serious treatise on the nature of law. But though the subject itself was profound, this gravitas did...