Carl Sandburg, Abraham Lincoln: The War Years. NY: Harcourt Brace, 1939—
Just why Lincoln took to whiskers at this time nobody seemed to know. A girl in New York had begged him to raise a beard. But something more than her random wish guided him. Herndon, Whitney, Lamon, Nicolay, Hay, heard no explanation from him as to why after fifty-two years with a smooth face he should now change.
Would whiskers imply responsibility, gravity, a more sober and serene outlook on the phantasmagoria of life? Perhaps he would seem more like a serious farmer with crops to look after, or perhaps a church sexton in charge of grave affairs. Or he might have the look of a sea-captain handling a ship in a storm on a starless sea. Anyhow, with whiskers or without, he would be about the same-sized target.