You cite Madison's "flip-flop" and then apply the in relation to the S. Carolina "efforts" to nullify, even secede and then ascribe the notion that the Founder's implicite and explicit intent was found in this letter. I can assure you that you are wrong...or Jefferson (and a younger Madison) in 1798 were not founders...which is it? You can't have it both ways. Madison was an evolutionary founder and not completely consistent, I'm sure you understand that about him. As a federalist, he no doubt held a deeper desire for a more consolidated government so his letter is not some stunning new revelation about the "intent of the Founders." Far from it. Your bias towards a consolidated can is exposed; that's fine. Mine is towards State sovereignity which was not "surrendered" during ratification but "delegated." So, continue with your big-government propoganda...it's seen for what it is, meshed together letters and opinions.
I'll rely on historical LEGAL documents like the NY Ratification Document, paragraph 4:
"That the powers of government may be reassumed by the people whensoever it shall become necessary to their happiness; that every power, jurisdiction, and right, which is not by the said Constitution clearly delegated to the Congress of the United States, or the departments of the government thereof, remains to the people of the several states, or to their respective state governments, to whom they may have granted the same; and that those clauses in the said Constitution, which declare that Congress shall not have or exercise certain powers, do not imply that Congress is entitled to any powers not given by the said Constitution; but such clauses are to be construed either as exceptions to certain specified powers, or as inserted merely for greater caution.
What you cite is a signing statement which is designed to make people feel better about the commitment they are entering into, but carries no force of law.
It is the equivalent of a nod & a wink, or fingers crossed behind ones back. What the various states signed, when they ratified (and this explains why some took so long) was an “all in” agreement. There were no special deals.
Our Founders were those who first wrote the new Constitution, publicly supported it (i.e., The Federalist Papers), and then voted to confirm it.
They alone are entitled to tell us what was their Original Intent -- and that is a rather small group of men.
It certainly includes James Madison, Alexander Hamilton and John Jay -- the Federalists.
Those who voted against the new Constitution -- the anti-Federalists -- were not Founders, and their opinions were not the Founders' Original Intent.
And you may also be an anti-Federalist, and that's fine, it's a legitimate point of view, and can be argued reasonably.
But then you cannot at the same time claim the US Constitution is the source of authority for your opinions, because it's not.
You can't have it both ways.
As for Madison's "flip-flops" -- both real and alleged -- if you will study his words carefully, indeed the words of all True Founders, you'll see that whenever they approach the subject of "disunion", "disolving", "breaking the compact", "dissolution", or secession, etc., it is always with the subtext that this is an extreme measure only valid under extreme conditions such as "injury or oppression", and never authorized simply "at pleasure".
But none of those extreme conditions existed in November 1860, and so those Deep-South slave-holders who organized, met and declared their secession were doing so strictly "at pleasure."
And not even Southern sympathizing Dough-faced President Buchanan could accept their actions as constitutional or lawful, though he refused to take any serious actions to oppose them.
By the way, I've recently found a partial listing of Federal properties unlawfully seized both before and after formal declarations of secession.
It's an impressive list, including: