"It will be admitted on all hands, that with the exception of the powers surrendered by the Constitution of the United States, the people of the several States are absolutely and unconditionally sovereign within their respective territories. It follows that they may impose what taxes they think proper upon persons or things within their dominion, and may apportion them according to their discretion and judgment. They may, if they deem it advisable to do so, exempt certain descriptions of property from taxation, and lay the burden of supporting the government elsewhere. And they may do this in the ordinary forms of legislation or by contract, as may seem best to the people of the State. ... For it can never be maintained in any tribunal in this country, that the people of a State, in the exercise of the powers of sovereignty, can be restrained within narrower limits than those fixed by the Constitution of the United States, upon the ground that they may make contracts ruinous or injurious to themselves. The principle that they are the best judges of what is for their own interest, is the foundation of our political institutions."