We are told that admitting a State into the Union is a compact. Yes, but what sort of a compact? A compact that it shall be a member of the Union, as the Constitution has made it. You cannot new fashion it. You may make a compact to admit, but when admitted the original compact prevails. The Union is a compact, with a provision of political power and agents for the accomplishment of its objects. Vary that compact as to a new State--give new energy to that political power so as to make it act with more force upon a new State than upon the old--make the will of those agents more effectually the arbiter of the fate of a new State than of the old, and it may be confidently said that the new State has not entered into this Union, but into another Union. How far the Union has been varied is another question. But that it has been varied is clear.
If I am told that by the bill relative to Missouri, you do not legislate upon a new State, I answer that you do; and I answer further that it is immaterial whether you do or not. But it is upon Missouri, as a State, that your terms and conditions are to act. Until Missouri is a State, the terms and conditions are nothing. You legislate in the shape of terms and conditions, prospectively--and you so legislate upon it that when it comes into the Union it is to be bound by a contract degrading and diminishing its sovereignty--and is to be stripped of rights which the original parties to the Union did not consent to abandon, and which that Union (so far as depends upon it) takes under its protection and guarantee.
Is the right to hold slaves a right which Massachusetts enjoys? If it is, Massachusetts is under this Union in a different character from Missouri. The compact of Union for it, is different from the same compact of Union for Missouri. The power of Congress is different--everything which depends upon the Union is, in that respect, different.
But it is immaterial whether you legislate for Missouri as a State or not. The effect of your legislation is to bring it into the Union with a portion of its sovereignty taken away.
But it is a State which you are to admit. What is a State in the sense of the Constitution? It is not a State in the general--but a State as you find it in the Constitution. A State, generally, is a body politic or independent political society of men. But the State which you are to admit must be more or less than this political entity. What must it be? Ask the constitution. It shows what it means by a State by reference to the parties to it. It must be such a State as Massachusetts, Virginia, and the other members of the American confederacy--a State with full sovereignty except as the constitution restricts it.