. >> stahl: after agreeing to take the part, daniel day-lewis spent a year reading and doing research into abrahamen you first approach him, because of the way he was as a man. as you begin to discover him, it's almost as if he welcomes you in. >> "lincoln": tell us the news from the hill. >> ah, well the news... >> "lincoln": why, for instance, is this thus, and what is the reason for this thusness? >> stahl: so much about daniel day lewis' portrait rings true to the man, including things most of us didn't know, like what lincoln sounded like. >> day-lewis: there are numerous references to him having a high- pitched voice. >> stahl: did that influence you? >> day-lewis: it's a clue, i suppose. all clues are potentially helpful. >> "lincoln": and come february the first, i intend to sign the 13th amendment. >> doris kearns goodwin: that's definitely the way people who heard him speak at the time said he spoke. so, somehow, he mastered that voice. >> stahl: even lincoln historians, like doris kearns goodwin, who was a consultant on the movie, say the portrait, down to the high voice, was eerily aut