Quote from ahoaho
The Wizard is more like a blues song, but Tony Iommi's tone defines the heavy metal tone. And if you want an analogous style, look at doom metal and sludge. Pantera, Down, Crowbar, and My Dying Bride have the same aesthetic to them. I disagree on War Pigs/Luke's Wall because of the chorus riff and the Luke's Wall riff and Jack the Stripper/Fairies Wear Boots, because of the Fairies wear boots riff.
Listen to Sabbath Bloody Sabbath, Paranoid, Death Mask/Into the Void, Black Sabbath, Nativity in Black, and Electric Funeral and tell me those are not metal songs.
I'll admit that part of the chorus of War Pigs has a metalish riff but that absoluetly is not enough to justify saying the whole thing is metal when most of the riffs are very much hard rock and nothing in the solos is even slightly metal. As for Fairies Wear Boots, I hear nothing even slightly metal in it. Neither of these songs have metal drums and the vocals are at most metal in their lyrics.
Yes Paranoid, Death Mask/Into the Void, Nativity in Black, ect are obviously metal but take an overall look at what they done and you end up with maybe half of their songs (with Ozzy) being something that people would still call metal.