CW Buff said:
Let's say, for a moment, that the states, which were fully sovereign prior to the Constitution, decided they wanted to create a union in which sovereignty is divided between the Union and the individual states. They were sovereign, so they could certainly do whatever they wished with their sovereignty. Sovereignty being what it is, the only legal transfer of sovereignty is a voluntary one, and the states being republican in nature, a majority of the people of each state would therefore have to approve the transfer of a portion of their sovereignty (that portion associated with the government powers enumerated in the to the Constitution) to the people of the US. In other words, the fact that "each state ratified for itself, and for itself only" says nothing about what the states were after they ratified the Constitution, but only what they were before.
You seem to like Madison, so here is one for you:
"Should all the states adopt it, it will be then a government established by the thirteen states of America, not through the intervention of the legislatures, but by the people at large." -- James Madison, VA state ratifying convention, June 6, 1788
"At large," meaning as a whole, a sovereign whole, e.g. "We the People of the United States of America." Again, the Constitution, and the state (the more perfect Union) and government (the Fed) it forms, can only be altered 1) as specifically provided for in the Constitution; or 2) as the sovereign people who ordained and established it wish, acting via the constitutional amendment process. The Constitution has a designated method for adding states to the Union, it has none for deducting them. That is therefore a matter to be decided by the sovereign people of the US, i.e., "the people" as referred to in the Tenth Amendment.
Here's another one for you:
"The Constitution requires an adoption in ." -- James Madison to Alexander Hamilton, July 20, 1788