Thomas Jefferson’s observations on the institution of slavery, 1781:

“And can the liberties of a nation be thought secure when we have removed their only firm basis, a conviction in the minds of the people that these liberties are of the gift of God  That they are not to be violated but with his wrath?  Indeed I tremble for my country when I reflect that God is just; that his justice cannot sleep for ever; that considering numbers, nature and natural means only, a revolution of the wheel of fortune, an exchange of situation, is among possible events; that it may be come probable by supernatural interference!  The Almighty has no attribute which can take side with us in such a contest.  But it is impossible to be temperate and to pursue this subject through the various considerations of policy, of morals, of history natural and civil.  We must be contented to hope they will force their way into every one’s mind.  I think a change already perceptible, since the origin of the present revolution.  The spirit of the master is abating, that of the slave rising from the dust, his condition mollifying, the way I hope preparing, under the auspices of heaven, for a total emancipation, and that this is disposed, in the order of events, to be with the consent of the masters, rather than by their extirpation.

– Thomas Jefferson, Notes on the State of Virginia, Query XVIII