Please tell me how come: * the colonies of Britain can secede, becoming individual sovereign States; * Texas can secede from Mexico, becoming a sovereign State; * the individual sovereign States can secede from the Articles of Confederation, formed in "perpetual union;" * the counties of western Virginia can secede from Virginia and accepted by the US as a sovereign State in violation of Article IV, Section 3 of the US Constitution; * but South Carolina and the rest of the South cannot secede from the US not formed in "perpetual union?"