Sale says some crazy things about WMDS, the economy, foreing policy, and other matters, but as far as the legality of secession, he hits the nail on the head.
Secession should be a last resort, but when the constitutional limits have totally disasppeared and every other means has been tried, secession is the states' trump card. By quashing it, Lincoln essentially empowered the Federal government to exercise absolute power.
BINGO!
While many people rightly believe government can only posses the authority given to it by the People, no one can explain where the right to force a State to stay in the Union can be found.
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A visitor to your home cannot be forced to stay past the point in which he wishes to leave. If, as individuals, we do not have the legitimate authority to force someone to associate with us against their will, how could we ever have given that power to the State governments? If the State governments can't posses that power, how did they give it to the federal government?
The beast we live under today is a far cry from the Freedom of the Founders.