This was written by the legendary Blues songwriter Willie Dixon, who often wrote about mystical themes in his songs like "Hoochie Coochie Man
." Dixon explained to Paul Zollo in a 1988 interview: "The seventh son is part of the scriptures of the Bible. 'The seventh son of the seventh son born on the seventh hour of the seventh day of the seventh month.' I was born in the seventh month and I was the seventh child of my family."
Mose Allison told Zollo: "I thought that was a great song of that type. One of the common things is to feel that you are supernatural sometimes. And most people have felt that at one time or another." (this appears in Zollo's book Songwriters On Songwriting