That was a decisive moment in Lincoln's career, and that's the situation he faced when he got up to give his House Divided speech on June 16th of 1858. It was a crisis of his own career. It was also, in my opinion, the gravest crisis this country has ever faced, because the greatest danger to the future of the country came not, I think, from the pro-slavery argument, but from the morally neutral argument of Douglas. And that's a long story and you'll find it all spelled out in great detail in my book, which I hope you will read with great care.

The Real Abraham Lincoln: A Debate (2002)