§ 20 Practical Law
Yet another kind of law is that which consists of rules for the attainment of some practical end, and which, for want of a better name, we may term practical law. These laws are the rules which guide us to the fulfilment of our purposes; which inform us as to what we ought to do, or must do, in order to attain a certain end.67 Examples of such are the laws of health, the laws of musical and poetical composition, the laws of style, the laws of architecture, the rules for the efficient conduct of any art or business. The laws of a game, such as whist, are of two kinds: some are conventional, being the rules agreed upon by the players; others are practical, being the rules for the successful playing of the game.