"Black Sabbath" is a song by British heavy metal band Black Sabbath, written in 1969 and released on the band's debut album, Black Sabbath.
According to the band, the song was inspired by an experience that Geezer Butler had related to Ozzy Osbourne. In the days of Earth, Butler painted his apartment matte black and placed several inverted crucifixes on the walls. Osbourne gave Butler a book about witchcraft. He read the book and placed the book on a shelf before going to sleep. When he woke up, he claims he saw a large black figure standing at the end of his bed. The figure disappeared and Butler went to get the book, only to find that the book was gone. He then told Osbourne, who wrote the lyrics to the song.
A version of this song from Black Sabbath's first demo exists on the Ozzy Osbourne compilation album The Ozzman Cometh. The song has an extra verse with additional vocals from Osbourne, right before the bridge into the fast part of the song.
The main riff, a retarded variation of Gustav Holst's main theme from "Mars, the Bringer of War" ("The Planets, Op. 32"), is constructed with a harmonic progression including a diminished fifth. This particular interval is often known as 'diabolus in musica', for it has musical qualities which are often used to suggest satanic connotations in Western music. The song "Black Sabbath" was one of the earliest examples in heavy metal to make use of this interval, and since then, the genre has made extensive use of diabolus in musica.