Heavy metal music
Critics disagree over who can be thought of as the first heavy metal band. Most credit either Led Zeppelin or Black Sabbath, with American commentators tending to favour Led Zeppelin and British commentators tending to favour Black Sabbath, though many give equal credit to both. A few commentators—mainly American—argue for other groups including Iron Butterfly, Steppenwolf or Blue Cheer. Deep Purple, the third band in what is sometimes considered the "unholy trinity" of heavy metal (Black Sabbath, Led Zeppelin, and Deep Purple), despite being slightly older than Black Sabbath and Led Zeppelin, fluctuated between many rock styles until late 1969 when they took a heavy metal direction.
Heavy metal lyrics
There were "heavy"-sounding bands before Black Sabbath, such as Led Zeppelin and Cream. However, the use of "dark and aggressive music" and "offensive lyrics" at the same time was started by Black Sabbath. Black Sabbath 's second album "Paranoid" (1970) "included songs dealing with personal trauma—'Paranoid' and 'Fairies Wear Boots' (which described the unsavoury side effects of drug-taking)—as well as those confronting wider issues, such as the self-explanatory 'War Pigs' and 'Hand of Doom.'" Deriving from the heavy metal genre's roots in blues music, sex is another important topic—a thread running from Led Zeppelin's suggestive lyrics to the more explicit references of glam metal and nu metal bands. Some themes are excluded in most heavy metal, such as optimistic, hope-filled songs, songs about romantic love or songs with a 1960s counterculture message of trying to change the world. In general, metal lyrics are not lighthearted and they do typically not make use of satire. Music critic Robert Christgau has called metal "an expressive mode it sometimes seems will be with us for as long as ordinary white boys fear girls, pity themselves, and are permitted to rage against a world they'll never beat".