Lethe alpha literally means "un-forgetfulness" or "un-concealment". Lethe, the river of forgetfulness, was one of the five rivers of the Greek underworld, the other four being Styx, Acheron (the river of sorrow), Cocytus (the river of lamentation) and Phlegethon (the river of fire). According to Statius, it bordered Elysium, the final resting place of the virtuous. Ovid wrote that the river flowed through the cave of Hypnos, god of sleep, where its murmuring would induce drowsiness. The shades of the dead were required to drink the waters of the Lethe in order to forget their earthly life. In the "Aeneid", Virgil
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),