the last book I ever read (Rise to Greatness by David Von Drehle, excerpt three)

from Rise to Greatness: Abraham Lincoln and America’s Most Perilous Year by David Von Drehle:

Lincoln faced no greater challenge than that of holding these vastly differing parties together long enough for the war’s own nature to reveal itself. To him, human history was an inexorable current that sometimes meandered, sometimes raged, but ultimately found its own course. And although it was his oft-spoken view that history was flowing away from slavery toward freedom, he believed that his most important responsibility was to keep the Union from breaking up short of that destination.

So while abolitionists pressed him for a war on slavery and conservatives pleaded with him to submerge the issue, Lincoln was steering a middle way, guided by two principles. First, his actions must be consistent with the Constitution; this would show Northern conservatives that he was not a radical, and simultaneously protect his flank against Chief Justice Taney. In Lincoln’s view, this principle, however sensible, severely limited his options, because the Constitution specifically recognized the existence of slavery and the right of states to maintain it. His second principle was that he would work through his options starting with the most cautious initiatives, because he understood that with each step he took on this volatile issue, there was no going back. Overreach could be fatal, so he would have to make his way forward very carefully, even as the world around him was aflame. Lincoln never claimed to “comprehend the whole of this stupendous crisis,” nor to “fully understand and foresee it all,” he once said. “And that being the case, I can only go just as fast as I can see how to go.”