30 Seconds to Mars (album) the ancient Chinese military treatise "The Art of War", attributed to Sun Tzu. The track "Revolution", excluded from the final track listing, was considered by some critics as having an anti-American tone. Leto rejected the claim and explained that it can be taken "many different ways" and if taken literally or politically, it could be misinterpreted. He said that the band "didn't want a song like that to overshadow what we are about" and especially after the September 11 attacks, they felt it did not fit thematically with the rest of the album, stating that "it took on new dimensions".
The Book of Taliesyn band's singer Rod Evans are very functional to the music and the marketing Deep Purple's record label was building up for the American hippie audience. Evans took inspiration for the fantasy-themed "Listen, Learn, Read On", which contains lyrical reference to the album's title, from the 14th-century Welsh manuscript Book of Taliesin, a collection of poems attributed to the 6th-century poet Taliesin. The title and cover art of the album were also inspired by the manuscript. Instead psychedelia and its rituals play a large part in the lyrics of "Shield". Simper thinks that Evans' lyrics are "far better than anything (...)