Voto:
The Cream are a blues rock group, proto-hard (these definitions are ridiculous), the Black Sabbath are the natural evolution of the Cream, the Priest of the Sabbath. "Sad Wings of Destiny" is a fundamental album for metal, while still being firmly anchored to hard rock (Victim of Changes, Deceiver, The Ripper, Tyrant, and apart from the ballads, the others too). Moreover, there's another band that contributed significantly to the birth of metal, the Scorpions: the dual guitar solos, the gloomy and slow ballads, the voice (powerful), dual guitar riffs... For instance, in 1976 (with the album "Virgin Killer"), the Scorpions were already more metal than Judas Priest. In 1973, Nazareth released "Razamanaz," the title track is just a breath away from metal, with powerful guitars, drums (with double bass, another characteristic of metal) like a pneumatic hammer, a voice like sandpaper, while the lyrics are the only ones that don't have any metal characteristics. Then, in 1974, Sweet composed two tracks, "Set Me Free" and "Sweet FA," which seem almost to be released from 1980 or thereabouts, so metal they are: compared to Sad Wings of Destiny, they are light-years ahead (in terms of metal, not quality). In 1976, QUEEN composed songs like "Tie Your Mother Down" and "White Man," which in their heavy and catchy progression, despite being hard rock, have many points in common with metal. Sad Wings of Destiny, while being an excellent album, still lacks the rhythmic and guitar heaviness (in a good sense, heavy) of these two tracks. That said, I acknowledge that Sad Wings blah blah is very important for laying down some of the main frameworks of metal (as already mentioned, two guitars, slow and relentless ballads...), but I believe (and I am not alone) that it is still a hard rock album. But then again, metal is a natural evolution of hard rock, so I don't see why there should be such a fierce debate about it. By the way, in 1976, "Rising" by Rainbow was released, perhaps the only album among all those mentioned earlier that was closest to metal at the time.