Vol 4

Black Sabbath Vol. 4 is the fourth album by the British heavy metal band Black Sabbath, released in September 1972.
Vol. 4 demonstrates Black Sabbath beginning to experiment with the heavy sound they had become known for. Although some of the album's songs are in their trademark style, others demonstrate a more sensitive approach which the band had never attempted before. This is best exemplified by the song "Changes". Written by Tony Iommi, it is entirely in the form of a piano ballad with mellotron. Although the band had used piano on some songs previously, it had played only a minor role in the songs.
At least two songs on the album reference the use of cocaine, with the lyrics and title of "Snowblind" being an example of this. "Cocaine" is whispered quite audibly after the first verse, approximately 41 seconds into the song. (During live performances Osbourne would typically scream the word at the top of his lungs after every verse.)