I’ve already provided Jefferson’s statements evidencing his opinion that states had the right of unilateral secession.
As to the 3 states’ express provisos made at the time of constitutional ratification reserving their right to secede, they are prima facia evidence as to what the parties to the compact agreed to at the time. They clearly thought they did have the power to unilaterally secede. Under the Comity Principle, every state understood itself to have that right. Nobody at the time said a state did not have that right or that reserving that right in any way clashed with the constitution.
If say, the citizens of Vermont democratically choose to leave, why should the rest of us use threats, force and violence to compel them to stay? Should marital partners be able to use violence to force their spouses to stay in a “perpetual union” they no longer wish to be a part of?
Doesn’t government derive its legitimacy from the consent of the governed as the Declaration of Independence proclaims?
I would let them depart in peace, wish them well and offer to set up mutually beneficial trading arrangements. I’m not an authoritarian. I have no wish to dictate to others - I just don’t want others trying to dictate to me.
It’s OK if you can’t provide the evidence - I understand.
But you haven't posted anything yet that actually shows him advocating secession - especially unilateral secession.