No Gradual Emancipation.

A mass convention was held yesterday in Memphis, inaugurating a general movement in Tennessee for the reorganization of the civil government in the State. One of the features of the call, we observe, is that "emancipation immediate and unconditional is our best and only true policy." The Unionism of the State has settled firmly on that principle.

It is extraordinary how completely the idea of gradual emancipation has been dissipated from the public mind everywhere, by the progress of events. Before the rebellion, it was accounted the very extreme of AntiSlavery fanaticism to believe in the possibility of immediate emancipation without social ruin. The wisest Anti-Slavery men of the day, whether in this country or in Europe, assumed it almost as an axiom that there could be no transition from Slavery to freedom without an apprenticeship, or some other arrangement that should deaden the shock. All of the acts of emancipation by England and the continental nations, and by our own Northern States, whenever they applied to more than a mere handful of slaves, were invariably based on that assumption. It took our own State not less than twenty-eight years to consummate the gradual extinction of the system after the Emancipation Law was passed. Long after the rebellion opened, even when it had become a generally accepted fact that Slavery must come to an end, the idea still adhered that the emancipation must be gradual in order to be safe. President LINCOLN, in his recommendation to Congress of appropriations to induce the Border States to initiate a system of emancipation, was particular to make it apply only to gradual emancipation. Even so late as last June, the Missouri Convention passed its emancipation ordinance so framed that no slave should go free before 1870, and the younger ones not until long afterwards.

But all these gradual methods are now hardly more thought of than if they had been obsolete a century. The people of Missouri, through their Legislature, have convened another convention to make a complete end of Slavery without delay. In Maryland immediate emancipation is the order of the day. The convention to frame the Free State Constitution, which is to be elceted on the first Wednesday of April, and to meet on the last Wednesday of the same month, will not think of adopting any other plan. In Louisiana, in Arkansas, in Florida, and in fact wherever the purpose of emancipation is entertained at all, there seems to be an almost unanimous agreement that immediate emancipation is the wisest, and in fact the only practicable method.

The change of opinion on this subject is a remarkable illustration of the practical aptitude of the American mind. With hardly an effort, theories and prejudices, that had apparently rooted themselves in it so deeply as to become a part of it, are discarded, and new ideas, in keeping with a new condition of affairs, are conceived, and conformed to, almost by universal consent. It is recognised that whatever may be the advantage theoretically of gradual over immediate emancipation, the actual situation permits no option between the two. Gradual emancipation is, in truth, no longer a debatable matter, for there is nothing really left to graduate. Slavery now exists only in name. Its substance has been destroyed by the terrible attrition of the war. As was said by Hon. THOS. SWANN, of Maryland, the other day, in convention: "The relation of master and slave is totally changed. The slave has become the master -- that is to say, he dictates his own terms of labor, or he goes where he can enjoy his unrestrained freedom without interference." This is the case in all of the old Slaveholding States now within our army lines; and each rebel State will come into just that condition just as soon as it is occupied by our armies. When the military arm once has play, there is no such thing as a gradual severance of the bond between the master and slave. The rupture is instantaneous, and complete, and permanent. To undertake to renew the relation between master and slave for the sake of destroying it more scientifically would be only to prolong social confusion, and work unmixed evil to both races.

This universal disposition of the slave holding States -- those which never joined the rebellion, and those which have been reclaimed from the rebellion -- to adopt emancipation voluntarily, as their only true policy, and to make immediate and sweeping work of it, serves to show how little practical effect, after all, will attach to anything Congress does, or leaves undone, on this subject. Were the proposed amendment of the Constitution, prohibiting Slavery everywhere within the limits of the United States, to be referred by Congress to-morrow to the various States for their adoption, it could scarcely be consented to by three-fourths of the several States, as the Constitution requires, before the very name and semblance of Slavery would have disappeared, so that the Amendment would have no more practical application than if it related to the Hindoo castes, or to the feudal system of the Middle Ages. It would take at least a year or eighteen months for all the twenty-seven States -- the requisite number -- to act through their Legislatures, many of which Legislatures only meet biennially. Before that time every reorganized rebel State will be living under a free State Constitution of its own adoption, as independent of the operations of any such amendment as Massachusetts or Michigan. If there be rebel States at that time still without a loyal free State organization, it will be only because they are stil unconquered, and no Constitutional amendment can facilitate conquest. That is military work exclusively; but work the very finishing of which finishes Slavery also.