If A. Can Prove, However Conclusively, That He May, Of Right Enslave B, Why May Not B Snatch The Same Argument, And Prove Equally, That He May Enslave A.

If A. can prove, however conclusively, that he may, of right enslave B,
why may not B snatch the same argument, and prove equally, that he
may enslave A. You say A is white and B is black. It is color, then;
the lighter, having the right to enslave the darker? Take care. By
this rule, you are to be slave to the first man you meet with a fairer
skin than your own.
You do not mean color exactly? You mean the whites are
intellectually the superiors of the blacks and therefore have the right
to enslave them? Take care again. By this rule, you are to be slave to
the first man you meet with an intellect superior to your own.
But, say you, it is a question of interest; and, if you can make it
your interest, you have the right to enslave another. Very well. And
if he can make it his interest, he has the right to enslave you.
-- Abraham Lincoln, 1854.