What is the summary of "If I Forget Thee, O Earth?"

Arthur C. Clarke’s short story “If I Forget Thee, Oh Earth . . .” tells the post-apocalyptic story of ten-year-old Marvin and his father. When the story opens, the two are ascending higher and higher up the various floors of the colony in which they live. After passing through the uppermost levels, the boy realizes that he is going to go somewhere he has never gone before.

He had seen it in photographs, of course: he had watched it imaged on television screens a hundred times. But now it was lying all around him, burning beneath the fierce sun that crawled so slowly across the jet-black sky.

Marvin, we learn, has never been outside of the colony before, and much of the story details his confusion at the various sights. The boy’s confusion is mirrored by the reader’s own, as much of the setting is ambiguous, but based on the black sky and their vehicle’s moon tires, at this point we can begin to infer that the two are on the moon.

After what seems to Marvin to be an eternity, the two descend into a valley, and Marvin “slowly realized that something very strange was happening in the land ahead.” Marvin looks out, and for the first time, he sees Earth with his own eyes, something that previously he was only able to see through photos and television.

For no warmth at all came from the great silver crescent that floated low above the far horizon and flooded all this land with pearly light. It was so brilliant that minutes passed before Marvin could accept its challenge and look steadfastly into its glare, but at last he could discern the outlines of continents, the hazy border of the atmosphere, and the white islands of cloud. And even at this distance, he could see the glitter of sunlight on the polar ice.

In this moment, Marvin realizes why his father has taken him on this adventure. Although neither Marvin’s father nor Marvin himself will live long enough to return to Earth—which has been destroyed by unexplained forces—eventually, Marvin’s children or his children’s children might. This, Marvin realizes, is what the colony continues to fight for and why it cannot give up hope:

That was the dream: and one day, Marvin knew with a sudden flash of insight, he would pass it on to his own son, here at this same spot with the mountains behind him and the silver light from the sky streaming into his face.