Bear in mind, also, and the fact is an important one, that the framers of the Constitution sat with doors closed, and that this was done purposely, that nothing but the result of their labours should be seen, and that that result should be judged of by the people free from any of the bias shown in the debates. It should also be borne in mind, and the fact is still more important, that the debates in the convention that framed the Constitution, and by means of which a pro-slavery interpretation is now attempted to be forced upon that instrument, were not published till more than a quarter of a century after the presentation and the adoption of the Constitution.
The Constitution of the United States: Is It Pro-Slavery or Anti-Slavery? (1860)