“Archibald MacLeish, "At the Lincoln Memorial", stanza 4, lines 1-6, and stanza 5, New & Collected Poems, 1917-1976 (1976), p. 433-35. This poem was written for ceremonies marking the centennial of the Emancipation Proclamation and was read by MacLeish at the Lincoln Memorial, Washington, D.C., (22 September 1962)”

Source: Wikiquote