I am loathe to close. We are not enemies, but friends. We must not be enemies. Though passion may have strained, it must not break our bonds of affection. The mystic chords of memory, stretching from every battlefield and patriot grave, to every living heart and hearthstone, all over this broad land, will yet swell the chorus of the Union, when again touched, as surely they will be, by the better angels of our nature.

Abraham Lincoln (1809-1865) American lawyer, politician, US President (1861-65)

Speech (1861-03-04), Inaugural Address, Washington, D. C. (final paragraph)
    (Source)

William Seward, though a political rival of Lincoln's, was invited by him to review the draft address. Seward suggested, as an added ending paragraph, the following, which was then adapted by Lincoln into the above:

I close. We are not, we must not be aliens or enemies but fellow-countrymen. Although passion has strained our bonds of affection too hardly, they must not, I am sure they will not, be broken. The mystic chords which, proceeding from so many battle-fields, and so many patriot graves, pass through all the hearts and all the hearths in this broad continent of ours, will yet again harmonize in their ancient music when breathed upon by the guardian angel of the nation.