Today we commemorate a monumental event in human history:

The first Black Sabbath album was released 40 years ago today. Cosmo at Invisible Oranges has a nice writeup about the album and its influence, which really can't be overstated. Suffice to say that if Black Sabbath didn't exist, neither would virtually all of the music I listen to. Keith points out here that metal doesn't stem from a single origin, though I sort of disagree with him. To be sure, Sabbath weren't the only heavy band at the time, but they were the first ones to bring the sense of evil and dread to their music. One of the reasons why the first Sabbath album is so interesting is that the band isn't yet a fully-formed heavy metal band yet: there's the crushing doom of tracks like "Black Sabbath" and "N.I.B."--the stuff that really spawned heavy metal--alongside more typical (for the time) heavy blues-rock tracks like "Evil Woman" (which didn't appear on the North American release on this album. Julian Cope discusses the significance of this here). Or as a writer for the Times has it:

It began with a clap of thunder and a tolling bell. Then, as a heavily distorted guitar played a diminished fifth — a tone sequence once banned by the Roman Catholic Church for being the “Devil’s interval” — a male voice started to wail as if from the grave. A few bars later the drums came in, and the resulting din was loud enough to make it seem as if Earth was coming apart at the seams.

Here's a video of Sabbath's performance in Paris in 1970: