If the Cotton States become satisfied they can do better out of the Union than in it, we insist on letting them go in peace. The right to secede may be revolutionary, but it exists. We hope never to live in a republic whereof one section is pinned to the residue by bayonets.
Original passage & context
"If the Cotton States shall become satisfied that they can do better out of the Union than in it, we insist on letting them go in peace. The right to secede may be a revolutionary one, but it exists nevertheless [...] whenever a considerable section of our Union shall deliberately resolve to go out, we shall resist all coercive measures designed to keep it in. We hope never to live in a republic, whereof one section is pinned to the residue by bayonets."
Written by editor Horace Greeley; his celebrated post-election editorial on the right of secession. The popular tag 'let the erring sisters depart in peace' is a later paraphrase — the phrase 'erring sisters' does NOT appear in the editorial, which says 'we insist on letting them go in peace.' Verified against Bonner's Mississippi Valley Historical Review (1951) reproduction, which prints the block quote in full and cites the Tribune of Nov 9, 1860; the original Tribune page-scan was not fetchable (LoC 403s; not digitized at the expected LCCN). Fragments joined with [...].
Read it in the original — New-York Tribune, Nov 9, 1860 (Bonner reproduction) ↗