666 was created as a concept album retelling the story of the Book of Revelation, the Apocalypse of John,[2] the book of the Bible that attacked on the tyranny of the Roman Empire at the time it was written, and the album goes through a number of famous passages and themes, including the Whore of Babylon (Rome), The Beast (Nero), and, in this case, the Four Horsemen of the Apocalypse.

The song's structure is marked by a dynamic contrast, with Roussos singing over an echoed keyboard drone and wind chimes in the verses,[3][4] and the chorus containing traditional rock instrumentation highlighted by Sideras' drumming.

[6] Receiving significant airplay on album-oriented radio, the song went on to be covered or sampled by a number of bands.

[9] The chorus was also sampled, in a slowed-down fashion, on Daniel Lopatin's "A7", from Chuck Person's Eccojams Vol.

[10] The song is popular among metal and techno acts, forming a significant list of covers and samplings.