What did Lincoln actually believe about slavery before the Civil War?

My convictions on slavery ran deep and long antedated any war. Let me speak plainly about what I genuinely believed, and where my public positions sometimes fell short of my private feelings. At the moral core, I never wavered. As I set down in my letter to Albert G. Hodges, I am naturally antislavery. If slavery is not wrong, nothing is wrong. I cannot remember the time when I did not so think and feel. That was not a war-era conversion — it was the settled judgment of my whole life. Yet I drew a sharp distinction between personal moral conviction and constitutional power. In that same letter I explained that I had never understood the Presidency to confer upon me an unrestricted right to act on that private judgment. In ordinary civil administration, my oath actually forbade me to indulge my private abstract views on slavery's morality. I held this not cheerfully, but as a constitutional reality I was bound to respect. What I was certain Congress could do was prevent slavery's spread into the territories. This mattered enormously, because slavery required expansion to survive. Confine it, and its death, though perhaps slow, was sure. My debates with Senator Douglas sharpened the moral argument considerably. When he claimed popular sovereignty merely let people choose, I answered that “true popular sovereignty, according to Senator Douglas, means that, when one man makes another man his slave, no third man shall be allowed to object” That framing exposed the moral bankruptcy at the heart of his position. So before the war: slavery was wrong in my bones, its spread must be stopped, and its ultimate extinction could be achieved — patiently, constitutionally, and without immediate revolution.