A secular hymn is a type of non-religious popular song that has elements in common with religious music, especially with Christian hymns. The concept goes back at least as far as 17 BCE when the Roman emperor Augustus commissioned the Roman poet Horace to write lyrics by that title. The idea has been recognized in popular music at least since the late 1960s and early 1970s when people began to see a pattern in songs, such as "Bridge Over Troubled Water" by Simon and Garfunkel, "Let it Be" by the Beatles, and "Fire and Rain" by James Taylor, which came out at about the same time. "Hallelujah" has since been called perhaps the quintessential secular hymn despite the lyrics containing strong Jewish themes.