In a very old interview done by Guitar World, Tony Iommi looked back on Bill Ward finding it difficult to play songs.

He said:

“During “Master of Reality”, we started getting more experimental and began taking too much time to record.”

“Ultimately, I think it really confused us. Sometimes I think I’d really like to go back to the way we recorded the first two albums [‘Black Sabbath’ and ‘Paranoid’].

“I’ve always preferred just going into the studio and playing, without spending a lot of time rehearsing or getting sounds.

“We tried recording ‘Into the Void’ in a couple of different studios because Bill [Ward, drums] just couldn’t get it right. Whenever that happened, he would start believing that he wasn’t capable of playing the song.

“He’d say, ‘To hell with it – I’m not doing this!’ There was one track like that on every album, and ‘Into the Void’ was the most difficult one on ‘Master of Reality.'”