According to the Shine a Light Songfacts, Mick Jagger originally wrote the lyrics for Stones guitarist Brian Jones in 1968. The original lyrics were about Jones' drug addiction which was slowly detaching him from the rest of the band, and the song was called "Get A Line On You," but it was never released. After Jones' death, Jagger rewrote some of the lyrics and it was released in 1972 as "Shine A Light."
Saw you stretched out in Room Ten O Nine
With a smile on your face and a tear right in your eye.
Oh, couldn't see to get a line on you, my sweet honey love.
Berber jewelry jangling down the street,