recorded with musical accompaniment for the first time in 1930 by Fiddlin' John Carson, although to another folk hymn named "At the Cross", not to "New Britain". "Amazing Grace" is emblematic of several kinds of folk music styles, often used as the standard example to illustrate such musical techniques as lining out and call and response, that have been practised in both black and white folk music. Mahalia Jackson's 1947 version received significant radio airplay, and as her popularity grew throughout the 1950s and 1960s, she often sang it at public events such as concerts at Carnegie Hall. Author James Basker states that the song has been employed by African Americans as the "paradigmatic Negro spiritual" because it expresses the joy felt at being delivered from slavery and worldly miseries. Anthony Heilbut, author of The Gospel Sound, states that the "dangers, toils, and snares" of Newton's words are a "universal testimony" of the African American experience. During the civil rights movement and opposition to the Vietnam War, the song took on a political tone. Mahalia Jackson employed "Amazing Grace" for Civil Rights marchers, writing that she used it "to give magical protection a charm to ward off danger, an incantation to the angels of heaven to descend ... I was not sure the magic worked outside the church walls ... in the open air of Mississippi. But I wasn't taking any chances." Folk singer Judy Collins, who knew the song before she could remember learning it, witnessed Fannie Lou Hamer leading marchers in Mississippi in 1964, singing "Amazing Grace". Collins also considered it a talisman of sorts, and saw its equal emotional impact on the marchers, witnesses, and law enforcement who opposed the civil rights demonstrators. According to fellow folk singer Joan Baez, it was one of the most requested songs from her audiences, but she never realised its origin as a hymn; by the time she was singing it in the 1960s she said it had "developed a life of its own". It even made an appearance at the Woodstock Music Festival in 1969 during Arlo Guthrie's performance. Collins decided to record it in the late 1960s amid an atmosphere of counterculture introspection; she was part of an encounter group that ended a contentious meeting by singing "Amazing Grace" as it was the only song to which all the members knew the words. Her producer was present and suggested