Slavery is the great and foul stain upon the North American Union... A dissolution, at least temporary, of the Union, as now constituted, would now be certainly necessary... The Union might then be reorganized on the fundamental principle of emancipation.
Diary entry (1820), as quoted in The Diary of John Quincy Adams (1951), by John Quincy Adams, Scribner's Sons, New York, p. 228-229