In truth, I swore to support the Constitution because I believe in it. I do not believe in their construction of it. It is as well known as any historical fact can be known, that the framers of the Constitution so worded it as that it never should recognize the idea of slave property. From the beginning to the ending of it.

As quoted in His Brother's Blood: Speeches and Writings, 1838–64 (2004), edited by William Frederick Moore and Jane Ann Moore, p. 199 - Speech to the U.S. House of Representatives (April 1860)