As is often the case on U2 albums, Bono is credited as the sole lyricist. In contrast to U2's previous records, whose lyrics were politically and socially charged, "Achtung Baby" is more personal and introspective, examining love, sexuality, spirituality, faith, and betrayal. The lyrics are darker in tone, describing troubled personal relationships and exuding feelings of confusion, loneliness, and inadequacy. Central to these themes was the Edge's separation from his wife (the mother of his three children), which occurred halfway through the album's recording. The pain not only focused him on the record and led him to advocate more personal themes, but it also affected Bono's lyrical contributions. Bono found inspiration from his own personal life, citing the births of his two daughters in 1989 and 1991 as major influences. This is reflected in "Zoo Station", which opens the album as a statement of intent with lyrics suggesting new anticipations and appetites.