Law, in its most general and comprehensive sense, signifies a rule of action; and is applied indiscriminately to all kinds of action, whether animate, or inanimate, rational or irrational. Thus we say, the laws of motion, of gravitation, of optics, or mechanics, as well as the laws of nature and of nations. And it is that rule of action, which is prescribed by some superior, and which the inferior is bound to obey.

Introduction, Section II: Of the Nature of Laws in General - Commentaries on the Laws of England (1765–1769)

Avalon Project - Blackstone's Commentaries on the Laws of England - Introduction[avalon.law.yale.edu]