A civilized community presupposes a government of law. If that government be a republic, its citizens are the sole sources, as well as the subjects of its power. Its constitution is their bill of directions to their own agents--a grant authorizing the exercise of certain powers, and prohibiting that of others. In the Constitution of the United States, whatever else may be obscure, the clause granting power to Congress over the Federal District may well defy misconstruction. Art. 1, Sec. 8, Clause 18: "The Congress shall have power to exercise exclusive legislation, in all cases whatsoever, over such District." Congress may make laws for the District "in all cases," not of all kinds. The grant respects the subjects of legislation, not the moral nature of the laws. The law-making power every where, is subject to moral restrictions, whether limited by constitutions or not. No legislature can authorize murder, nor make honesty penal, nor virtue a crime, nor exact impossibilities. In these and similar respects, the power of Congress is held in check by principles existing in the nature of things, not imposed by the Constitution, but presupposed and assumed by it. The power of Congress over the District is restricted only by those principles that limit ordinary legislation, and, in some respects, it has even wider scope.