his song arrangements and incorporates dissonance with chromatic melody and/or harmony. These techniques are all used in the song "Hurt", which contains a highly dissonant tritone played on guitar during the verses, a B5#11, emphasized when Reznor sings the eleventh note on the word "I" every time the B/E# dyad is played. "Closer" concludes with a chromatic piano motif: the melody is debuted during the second verse of "Piggy" on organ, then reappears in power chords at drop D tuning throughout the chorus of "Heresy", while an inverted (ascending) version is used throughout "A Warm Place", and then recurs in its original state for the final time on "The Downward Spiral". On The Fragile, Reznor revisits the technique of repeating a motif multiple times throughout different songs, either on a different musical instrument with a transposed harmony or in an altered tempo. Many of the songs on Year Zero contain an extended instrumental ending, which encompasses the entire second half of the three-minute long "The Great Destroyer". Allmusic's review described the album's laptop-mixed sound: "Guitars squall against glitches, beeps, pops, and blotches of blurry sonic attacks. Percussion looms large, distorted, organic, looped, screwed, spindled and broken." Lyrical themes found in Nine Inch Nails songs are largely concerned with dark explorations of the self ranging from religion, greed, fame, lust, addiction, self-deception, aging, regret, and nihilism. Occasionally, the lyrics depart from their introspective nature to deal with a topic like politics, which is the focus of Year Zero. Three Nine Inch Nails albums are concept albums: The Downward Spiral, The Fragile, and Year Zero. The album With Teeth was originally set to be a concept album about an endless dream occurring in reality, but Reznor eventually took this idea out of the record. Influences Nine Inch Nails' earliest influence was the punk rock band The Clash; Reznor stated that he started out trying to directly imitate them, only to abandon that direction due to his lack of a political message. Other early influences include Ministry and Skinny Puppy, which helped shape 1989's Pretty Hate Machine. The album's liner notes also paid tribute to Public Enemy and Prince. Another large influence on the band's sound is Gary Numan, which is evident as Reznor once said that "after hearing 'Cars' I knew I wanted to make music with synthesizers". The 2005 single "Only" exemplifies the disco-style beats and synthesizers drawn from Numan's persuasion.