they were betrayed, when they imparted to the work of their hands any power to contribute to the continuance of such a system.  They can only palliate it, by supposing, that they thought, slavery was already a waning institution, destined soon to pass away.  In their time, (1787) slaves were comparatively of little value—­there being then no great slave-labor staple (as cotton is now) to make them profitable to their holders.[A] Had the circumstances of the country remained as they then were, slave-labor, always and every where the most expensive—­would have disappeared before the competition of free labour.  They had seen, too, the principle of universal liberty, on which the Revolution was justified, recognised and embodied in most of the State Constitutions; they had seen slavery utterly forbidden in that of Vermont —­instantaneously abolished in that of Massachusetts—­and laws enacted in the New-England States and in Pennsylvania, for its gradual abolition.  Well might they have anticipated, that Justice and Humanity, now starting forth with fresh vigor, would, in their march, sweep away the whole system; more especially, as freedom of speech and of the press—­the legitimate abolisher not only of the acknowledged vice of slavery, but of every other that time should reveal in our institutions or practices—­had been fully secured to the people.  Again; power was conferred on Congress to put a stop to the African slave-trade, without which it was thought, at that time, to be impossible to maintain slavery, as a system, on this continent,—­so great was the havoc it committed on human life.  Authority was also granted to Congress to prevent the transfer of slaves, as articles of commerce, from one State to another; and the introduction of slavery into the territories.  All this was crowned by the power of refusing admission into the Union, to any new state, whose form of government was repugnant to the principles of liberty set forth in that of the United States.  The faithful execution, by Congress, of these powers, it was reasonably enough supposed, would, at least, prevent the growth of slavery, if it did not entirely remove it.  Congress did, at the set time, execute one of them—­deemed, then, the most effectual of the whole; but, as it has turned out, the least so.

[Footnote A:  The cultivation of cotton was almost unknown in the United States before 1787.  It was not till two years afterward that it began to be raised or exported. (See Report of the Secretary of the Treasury, Feb. 29, 1836.)—­See Appendix, D.]

The effect of the interdiction of the African slave-trade was, not to diminish the trade itself, or greatly to mitigate its horrors; it only changed its name from African to American—­transferred the seat of commerce from Africa to America—­its profits from African princes to American farmers.  Indeed, it is almost certain, if the African slave-trade had been left unrestrained, that slavery would not