"Lithium" explores the complex relationship with sorrow, depicting a love-hate dynamic with sadness itself. The word "Lithium" is used as a metaphor for numbness, reflecting a desire to break free from negative emotional cycles rather than embrace a state of not feeling. It's about wanting to move on and change, even when there's a strange comfort in familiar lows. Originally conceived on guitar when the singer was 16, the song was later completed on piano and released on the band's second studio album, The Open Door. At its heart, it plays like a journey through the tension between holding onto pain and yearning for liberation.