The Forbidden Fountain of Oz food, which occurs most famously in the "forbidden fruit" of the Tree of Knowledge of Good and Evil in the Book of Genesis, but in other contexts too. The idea of water that purges the drinker's memory is also ancient. In Greek mythology it occurs as the river Lethe: the souls of the dead lose their memories of their earthly lives by drinking its water. The same idea can also be found in Eastern and other literatures, as in the "Well of the Waters of Forgetfulness" and other guises. "The 'Drink of Forgetfulness' is found in Greek, Hindu, Norse, and
The Book of Souls purchase of Sanctuary Records in 2013. On 14 August, the band issued a music video for the song "Speed of Light", directed by Llexi Leon. In addition, the song was simultaneously made available as a digital download and was issued as a single-track CD via Best Buy in the US. "The Book of Souls" is the band's first album since 1995's "The X Factor" to use their original logo on the cover. The artwork was created by Mark Wilkinson, whose previous works for Iron Maiden include "Live at Donington" (1998 remastered version) and "Best of the 'B' Sides" (2002 compilation),