The idea of an American right of secession -- a state's right to abandon the union -- today invites a veritable cyclone of scorn and bafflement. Secessionism, you will be told, is immoral, treasonous, seditious, the failed machination of slave-holding Southerners whose nutty dream died in the judgment of 1865. "What insanity it is to reopen this issue," says Pauline Maier, professor of American history at MIT.What you will not hear is that secessionism is as old as the states themselves, that is was not always a reviled idea, that it cleaves to the heart of a celebrated but perhaps outmoded American principle -- the rebellion against centralized power -- and that it is a founding American act enshrined in our most revolutionary document. "[W]henever any Form of Government becomes destructive," counsels the Declaration of Independence, "it is the Right of the People to alter or to abolish it, and to institute new Government." Although secessionism today is politically impossible, if tenuously legal, the secession specter has arisen again, waking to the Declaration's call to self-governance. In 2005, it is the blue-state Northerners, bitter from the defeat of Nov. 2, who are, ironically, wearing its robes.