Artists who believed beauty was in their own minds and souls were expressionists.

Expressionists

There's a lot of speculation about this. The band themselves tend to indirectly cite a 1963 horror film of that name by Boris Karloff. Others have speculated that the US Acid Rock band Coven, and their 1969 album, Witchcraft Destroys Minds and Reaps Souls is where it was pulled from, citing the first track of that album (which was titled "Black Sabbath") and that Coven had a bassist who had taken on the name of Oz Osbourne (at the time of the release of the Coven album, Ozzy Osbourne was playing bass for a band called Magic Lanterns as John Osbourne). While the second makes for a more fantastic story, personally, I find the first one more likely.

Another name for Death. Reaper because he reaps their souls. Grim because of the death.