Abraham Lincoln was not philosopher, exactly. But he did have a strong mind, which sought generalizations as well as particulars. He had a terrific memory.

I am asked often about Abraham Lincoln's mistakes and faults; he certainly made some mistakes. I have chapter in President Lincoln about the Powhatan affair that was a royal screw-up in the early days - right alongside the Sumter affair. Lincoln signed letters he should not signed, and the ship was sent to two places at one under two captains etc. Fortunately, no great harm. Lincoln took the blame and did not do anything like that again.

It is very hard to answer the oft-posed questions about how Abraham Lincoln would respond to some current condition. My favorite story on that count is that the late great Lincoln scholar Don Fehrebacher was asked, during the struggles over bussing for racial balance a few years ago, what Lincoln would say about "bussing" and he thought awhile and then answered : "what Lincoln would say would be: "What's a bus?"

The situation Abraham Lincoln faced was unique. In his view, the United States was threatened with destruction, ruin, overthrow, perishing - all words that he used - which is not the case for any other president, including the current one - Barack Obama.

Abraham Lincoln did not contend that his actions were immune from Congressional correction; on the contrary, he specifically said he was acting beyond the present provisions in the expectation that congress would retroactively approve, which they did. He did not say anything like Richard Nixon: if the president does it is legal.

All presidents - particularly war presidents, presidents inclined to the imperial presidency - invoke Abraham Lincoln as a justification, but they omit these three defenses of Lincoln's strong actions. Suspend habeas, blockade, increase army without congress, arrest Maryland legislators, etc.

There was specific constitutional provision for emergency measures in the case that Abraham Lincoln faced - an insurrection - which no other president has faced.