It only takes the first two seconds of the first song on their first record for Led Zeppelin to make crystal clear exactly what they intend to do – and exactly what they intend to do to you. In the opening to "Good Times Bad Times," the band drops a two-note attack that falls like a cartoon safe, clearing the air for John Bonham’s syncopated groove, Jimmy Page's swift-sword guitar and Robert Plant's high-end howling about sex so loud it gets the neighbors talking. "It really wasn’t a pretty thing,” Plant later said. "It wasn't supposed to be a pretty thing. It was just an unleashing of energy."
When Led Zeppelin was released in January 1969, it went to the Top 10 in the U.S. and the U.K. charts, despite lukewarm reviews. The enormity of Zeppelin's innovation wasn't entirely easy to recognize. In an era of spiritual transcendence and tales of brave Ulysses, they’d flipped teenage rock & roll's sex-zonked mania into something huge and seething and mythic- bestial. Eastern mysticism and Mordor and prom-ruling radio gold would all come later. This was something purer: Zeppelin as all-id power station. It was heavy metal.
– Jon Dolan