reagan understood abraham lincoln. july 17, 1980 at the republican convention, reagan accepts the nomination. and he quotes lincoln. so president lincoln said "no administration by any extreme of wickedness or folly can seriously injure the government in the short space of four years." then reagan said, "if mr. lincoln could see what's happened in this country in the last three and a half years, he might hedge on that statement." in other words, the carter years. reagan also said in his inaugural, in 1981, "whoever would understand in his heart the meaning of america will find

it in the life of abraham lincoln." true. i think he got it. in 1984, when reagan was running for reelection, he said, i want to quote president lincoln. lincoln said, "we must distance -- disenthrall ourselves from the past and then we will save our country." and reagan went on to say, "four years ago, that's what we did. we saved the country." reagan said that he shared many points of philosophy with lincoln. a couple of times, he called him

father abraham. president george bush senior seemed to understand the duality of lincoln. he said, if you look at some of the paintings of lincoln, you see his "agony and his greatness." and he equates the two. he then also says, bush senior, lincoln was at once a hard and gentle person, a man of grief and yet of humor. president clinton used lincoln to argue that -- and said lincoln saw that it was the clear duty was to revive the american dream and then clinton said now the responsibility is

to revive the american economy. one thing my assistant found in the research, in january 1998 president clinton was here at the university of illinois talking about the land-grant colleges. it was not a particularly memorable speech. but at one point, and it is hard to believe this happened, but it did. clinton said, oh, i think lincoln would have liked the pep band. [laughter] i did a little checking and someone said he spotted someone he liked in the pep band. [laughter]

we'll never know. george w. bush, as president, talked about lincoln quite a bit. i did four books on george w. bush's wars in iraq. in one interview, he's trying to explain what his plan was after 9/11. and he said the following. "i am product of the vietnam era. i remember presidents trying to wage wars that were very unpopular and the nation split. he then points to a portrait of abraham lincoln that hung in the oval office. he said, "he is on the wall because the job of the president

is to unite the nation. that's the job of the president." president obama on lincoln, a month after obama's inaugural, he just said, "lincoln made by own story possible." and that's exactly true. i remember interviewing president obama about the afghan war for a book i did called "obama's wars" in 2010 about the decisions obama made. in a case like this -- i sent him a 15-page memo saying this is what i would like to ask

about obama. every president now lives in an environment where there are two questions. there are the press conferences, the shouted questions and there is a kind of gotcha environment. so when you send a long memo saying i've worked for a year on this and i would like to talk to you and here are the questions, presidents tend to respond. so when i am interviewing him about afghanistan and what his decisions were, you may recall in his first year he ordered 30,000 more american troops to the afghan war. i wanted to try to ascertain how he looked at war. because i am convinced it is very important that presidents be tough in their articulation of what the united states will

do and what it will do to preserve its interests. so at the end of the interview, i handed president obama a quote from a book from a former colleague at "the washington post" rick atkinson. in the middle of the book, rick pulls back and says i'm going to tell you about war. and this is the quote that i handed obama. it said essentially that war corrupts everyone. that war leaves no heart unstained because it is the necessary cause of killing other people.