Spielberg told EW that, while Day-Lewis did not channel Lincoln through full immersion as some reports claimed, he did capture "the intangible, pensive quality that made [Lincoln] a great leader."
Also, it didn't hurt the realism to be called "Mr. President" on set.
"I was calling [all] the actors by their character names," Spielberg is quoted as saying. "That was something I felt was important to establish a little authenticity, maybe even more for me than for them."
Co-starring Sally Field, Joseph Gordon-Levitt, Tommy Lee Jones, David Strathairn, James Spader, Lee Pace, Jackie Earle Haley, and Jared Harris as Ulysses S. Grant, Lincoln is set to open in theaters November 9th.