Biography

Mayo was born in Warwick, Massachusetts, and attended Amherst College in 1843. then illness and an interest in the ministry led him to begin studying theology . By 1846, Mayo was an ordained Universalist minister. His preaching style was reportedly appealing, enlightening, and spiritually uplifting, and his popularity led to increasing church attendance. Many of his sermons were collected in his works The Balance; or, Moral Arguments for Universalism (1847) and Graces and Powers of the Christian Life (1853.)
In 1846 Mayo married Sarah Edgarton (Sarah Carter Edgarton Mayo). Sarah died only two years after their marriage. In 1853 Mayo married Lucy Caroline Clarke. Mayo had five children.
In October 1854 Mayo resigned his duties at Gloucester and became pastor of the Independent Christian Church in Cleveland, Ohio, where he served for the next two years. In 1856 he relocated to Albany, New York, where he ministered at the Division Street Unitarian Church until 1863. In 1863 he accepted a position as preacher of the Church of the Redeemer in Cincinnati, Ohio.
In 1872 Mayo left Cincinnati to preach at the Church of the Unity in Springfield, Massachusetts. He retained his position in Springfield until 1880, when he resigned from active ministerial duties and devoted more time to writing and lecturing.
In 1880 Mayo's interests became more directed toward educational pursuits. With his move to Boston in 1880, his interest in education, particularly education in the South, became a driving force. For the next twenty years Mayo devoted himself to advancing Southern education. Traveling an estimated 200,000 miles, he lectured, delivered sermons, and consulted numerous southern educators. 
From 1880 to 1885 Mayo, between travels, served as associate editor of the New England Journal of Education and as chief editorial writer for the National Journal of Education. At the request of Dr. William T. Harris, U.S. commissioner of education, Mayo dedicated himself to writing the history of American common schools. The work was uncompleted at his death.
Between 1893 and his death, Mayo was a lecturer of education at Berea College, Kentucky. 
Mentioned in a letter from Lazette Worden to Sarah Hance on January 9, 1857, admiring his sermons.