Yet, I think there is something else - it is the words, as you say, but also the distinctive, almost unique facial appearance, in combination with his imposing 6'4" frame - the tallest of any of our Presidents (see http://www.laughtergenealogy.com/bin/histprof/misc/olio/personal.html ) - not one other President was within an inch of Lincoln's height.
Heck, David - Lincoln looked Presidential which must add something to his greatness in the minds of many. You tell me of any recent President that looked or looks "Presidential." Take away the height, the facial appearance and the words and you have something comparable to a modern President I won't mention.
Yet, I wonder if words, height, facial appearance were all? I think in some way, the critical circumstances of his days of his Presidential tenure also must have added to the current perception of his greatness.