There are people who will tell you this is the first heavy metal album of all time. And I understand why they say that, especially with the benefit of hindsight. I respectfully disagree with that particular claim and I think I have pretty valid reasons for doing so, but that doesn’t take away from both how utterly unique this record was for 1970 and also how massively influential it (and their entire oeuvre) ended up being, given how much of a critical bomb it was on its release.
The older I get, having now listened to way, way too much music, the more I am becoming convinced that there are very few instances of a “first” album in any genre. There are a few, perhaps, but there aren’t many. Music (and art) doesn’t work like that. Very few things are created sui generis, and this album is no exception. Heavy Metal existed before the release of this album, it just doesn’t sound like “metal” to most of us, because we weren’t alive for it and we weren’t even alive for the beginning of the second wave of metal.
But it’s easy to see how it can feel like the first metal album: Sabbath are slower, sludgier and louder than Zeppelin and they are both less clearly psychedelic than Blue Cheer and also far more occult than them too.
In fact, the lyrics play as much as part as the music in making this such a seminal metal release. Though Butler’s lyrics are often far more positive (and less occult) than they initially seem, he is still far more interested in the occult than most lyricists were at the time. And pairing his words with Ozzy’s voice, Iommi’s tuning and the bands overall vibe (not to mention the artwork) and you get the perception of something spooky and probably evil.
The material would get a lot better on the next record – though they would reuse the odd idea – but this one was still first and, as such, it established many of the central conventions of metal, many of which are still in play today, 50 years later.