"Celtic Soul" is a take off from Van Morrison's own designation of "Caledonia Soul Music." There’s a bootleg album entitled Van Morrison Meets Bob Dylan and John Lee Hooker (1970), which contains the track, “Caledonia Soul Music” [16:18]. (Though unreleased, this song was supposed to be an outtake of a recording session Van did at Pacific High Studios in 1971.)

The name "Caledonia" has played a prominent role in Van's life and career. Biographer Ritchie Yorke had pointed out already by 1975 that Van Morrison has referred to Caledonia so many times in his career that he "seems to be obsessed with the word." In his 2009 biography, Erik Hage found that "Morrison seemed deeply interested in his paternal Scottish roots during his early career, and later in the ancient countryside of England, hence his repeated use of the term Caledonia (an ancient Roman name for Scotland/northern Britain)." As well as being his daughter Shana's middle name, it's the name of his first production company, his studio, his publishing company, two of his backing groups, his parents' record store in Fairfax, California in the 1970s. Morrison used "Caledonia" in what has been called a quintessential Van Morrison moment in the song, "Listen to the Lion," with the lyrics: "And we sail, and we sail, way up to Caledonia." As late as 2008, Morrison used "Caledonia" as a mantra in the live performance of the song, "Astral Weeks," recorded at the two Hollywood Bowl concerts.

Van also created The Caledonia Soul Orchestra, his backup band, in 1973. The band was named after an eighteen-minute instrumental outtake on the His Band and the Street Choir album. In 1973, Van Morrison and the Caledonia Soul Orchestra went on a three-month tour of the United States and Europe, the result of which was the seminal live (compilation) double album It's Too Late to Stop Now  (1973). The title is taken from the last line in the lyrics in one of Morrison's songs: "Into the Mystic" from the 1970 Moondance album.