The roots of Gospel music stem from Negro Spirituals that transformed from Spirituals into Jubilee Quartets then turned to Gospel in the 1920s. Blues piano player, Thomas A.Dorsey, became known as the father of Gospel after he contributed to the rise in popularity and accessibility of Gospel music. After he lost a large amount of money, Dorsey took that as a sign to turn his talents into songwriting and focusing on his faith. Thomas focused on the sound, the music itself, while his wife, Sally Dorsey, crafted and perfected the business end of it. Sally merchandised gospel songs by selling her husband's music as sheet music. The similarities between Gospel and its roots can be heard via the use of call and response that originated in Negro Spirituals. What made Gospel unique was its explicit connection to Jesus and the church. Gospel broke up into subcategories after the 1920s such as Traditional, Transitional, Tindley Style, Rural Traditional, and Contemporary. A few notable Gospel artists and groups include Mahalia Jackson, Albertina Walker, Shirley Caesar, Jonathan McReynolds, Israel Houghton, Jonathan Butler, Travis Green, The Soul Stirrers, The Edwin Hawkins Singers, and The Caravans.