“If I Forget Thee, Oh Earth” focuses primarily on the themes of Coming of Age as an Individual and a Species, Legacy and the Relationship Between Fathers and Sons, and The Dangers of Technology. The physical journey in the moon vehicle parallels Marvin’s journey of discovery as he realizes what has happened to Earth and what humanity must do to survive in the aftermath, as well as the role he himself must play.

Clarke uses the somewhat naive perspective of the boy to convey his message about the dangers of atomic weapons and of human hubris. The use of third-person limited point of view encourages close identification between Marvin and the reader, who experiences the story through Marvin’s perspective. At the beginning of the story, Marvin’s reactions are those of a 10-year-old child: excitement at seeing firsthand what he has previously only known from photographs and educational materials. The lyrical language with which Clarke describes Earthrise further invites the reader into Marvin’s sense of wonder. The juxtaposition of childlike curiosity and delight with the reality of Earth’s devastation  aims to heighten the emotional impact of the climactic revelation.