What doesn't belong is your claim that our Founders ever favored disunion or secession "at pleasure", meaning absent either mutual consent or necessity caused by oppression & usurpations.
Remember their examples: 1) the Declaration of Independence included a long list of serious grievances against the British king, and those made independence necessary.
2) Replacing the old Articles of Confederation was done by mutual consent.
Again I say, if you care to learn what our Founders really believed on this subject, start with James Madison.
“What doesn’t belong is your claim that our Founders ever favored disunion or secession “at pleasure”, meaning absent either mutual consent or necessity caused by oppression & usurpations.”
Here’s the language for which you have been searching:
“The powers not delegated to the Unted States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people except that the powers reserved for the people can not be exercised at pleasure or without the mutual consent of the federal government.”
Isn’t this what you really believe?