Poet Carl Sandberg on Rainbows As "Arches": “Love stands and hangs by an arch. The rainbow is an arch. Hate and pride break arches. Love and understanding build unbreakable arches.”

Carl Sandberg, three time Pulitzer Prize winning poet and Lincoln biographer said it best.  From Wikipedia:

Carl August Sandburg (January 6, 1878 – July 22, 1967) was an American poet, writer, and editor. He won three Pulitzer Prizes: two for his poetry and one for his biography of Abraham Lincoln. During his lifetime, Sandburg was widely regarded as "a major figure in contemporary literature", especially for volumes of his collected verse, including Chicago Poems (1916), Cornhuskers (1918), and Smoke and Steel (1920).^[2]He enjoyed "unrivaled appeal as a poet in his day, perhaps because the breadth of his experiences connected him with so many strands of American life",^[3] and at his death in 1967, President Lyndon B. Johnson observed that "Carl Sandburg was more than the voice of America, more than the poet of its strength and genius. He was America."^[4]

From White House Historical Association Facebook post:

Sandburg later spoke about the Civil War in the Coolidge Auditorium at the Library of Congress. He concluded by imagining Lincoln and Confederate General Robert E. Lee shaking hands and remarking, “Love stands and hangs by an arch. The rainbow is an arch. Hate and pride break arches. Love and understanding build unbreakable arches.”

The White House Historical Association

October 12 at 2:01pm · 

Poetry and historic commemoration united in the visit of Carl Sandburg to the Kennedy White House on October 25, 1961. The 83-year-old Sandburg had achieved fame both as a poet and a historian, especially for several well-regarded works about President Abraham Lincoln. His visit to Washington, D.C., served as an opportunity for the poet to meet President John F. Kennedy at the White House, commemorate the centennial of the American Civil War, and display his notoriously feisty temperament.

Wearing a red tie and dark blue shirt, Sandburg began the day by meeting the president for a chat in his White House Oval Office. Accompanied by fellow poet Louis Untermeyer, he then had lunch with Interior Secretary Stewart L. Udall. The lunch took longer than expected, and he arrived at the Library of Congress 30 minutes late, telling waiting officials, “Let’s get going, let’s get going!”

After touring the exhibit, which he called the best he had ever seen, Sandburg agreed to an impromptu press conference, saying “They can ask enough questions in 10 minutes to get a man in trouble for his whole life.” He did not disappoint, giving “outspoken comments that drew a few blushes from listening women.”

Sandburg later spoke about the Civil War in the Coolidge Auditorium at the Library of Congress. He concluded by imagining Lincoln and Confederate General Robert E. Lee shaking hands and remarking, “Love stands and hangs by an arch. The rainbow is an arch. Hate and pride break arches. Love and understanding build unbreakable arches.”

The photograph shows Sandburg meeting with President Kennedy in the White House Oval Office on October 25, 1961.