Lincoln was not only a self-made man, but an improver par excellence. This is seen most clearly in his transforming of a paragraph William Seward suggested Lincoln use to conclude his first inaugural address: Lincoln’s revision of Seward’s formulations led him to develop that great closing phrase, "the better angels of our nature."
Regarding Safire’s essay on the Gettysburg Address, I should add that historian Don E. Fehrenbacher offers additional support for Lincoln’s deliberate use of a biblical locution for time—“Four score and seven years ago.” As I point out in my book, Lincoln’s Sacred Effort: Defining Religion’s Role in American Self-Government, Fehrenbacher suggested that Lincoln gleaned the opening sentence of his Gettysburg Address from a speech of Pennsylvania Congressman Galusha A. Grow.
When the 37th Congress first met in special session on July 4, 1861, Grow was elected Republican speaker of the House of Representatives. Early in his acceptance speech, Congressman Grow referred to the birth of the American nation in imagery strikingly similar to Lincoln’s over two years later at Gettysburg:
“Fourscore years ago fifty-six bold merchants, farmers, lawyers, and mechanics, the representatives of a few feeble colonists, scattered along the Atlantic sea-board, met in convention to found a new empire, based on the inalienable rights of man.”
Anticipating Lincoln’s Gettysburg Address, Congressman Grow dates the nation’s birth not to the ratification of the U.S. Constitution, but to the signing of the Declaration of Independence:
“Seven years of bloody conflict ensued, and the 4th of July, 1776, is canonized in the hearts of the great and the good as the jubilee of oppressed nationalities; and in the calendar of heroic deeds it marks a new era in the history of the race.”
Grow later refers to the time elapsed since the Declaration of Independence as “Three quarters of a century,” and, similar to Lincoln’s allusion to Psalms 90, observes that the anniversary of July 4th occurs “after a period but little exceeding that of the allotted lifetime of man.” Given Lincoln’s obvious desire to work with the newly elected Congress to put down the insurrection, it is quite likely that he read House Speaker Grow’s speech.
At Gettysburg Lincoln would adopt Grow’s biblical reference to the nation’s founding in a way that invested America’s birth and present struggle with spiritual significance. In a speech that makes no explicit reference to the Bible or Christianity, Lincoln still manages from the outset to imbue the dedication at Gettysburg with theological import.
More support for Lincoln’s deliberate allusion to the Psalms is found in a letter he wrote to a lifelong Democrat, 105-year-old Deacon John Phillips, who voted for both George Washington and Abraham Lincoln: “The example of such devotion to civic duties in one whose days have already extended an average life time beyond the Psalmist’s limit, cannot but be valuable and fruitful.” (To John Phillips (21 November 1864), in Collected Works of Abraham Lincoln, 8:118.)