theme and moral are accentuated by the title, which is taken from Psalm 137 in the Bible. This psalm is a lament of the Jews that have been carried into captivity in Babylon, far away from their beloved homeland. Verses 4 to 6 say:

How shall we sing the Lord's song in a strange land? If I forget thee, O Jerusalem, let my right hand forget her cunning. If I do not remember thee, let my tongue cleave to the roof of my mouth; if I prefer not Jerusalem above my chief joy.

Just as in this psalm the Jews passed on the love and longing for their homeland to their offspring, so the father in this story passes on the vision of the heritage of their homeland Earth to his son, trusting that his son, in turn, will pass it on to his descendants.

The imagery in the story reinforces the author's message. He describes the harsh landscape of the moon and contrasts it with the beauty of the Earth as seen from afar.

The setting is the moon in a future era. A boy is traveling with his father from his underground home, visiting the surface of the moon and seeing the stars with his own eyes for the first time ever.

The tone moves from the boy's sense of wonder at seeing space and the earth for the first time, to sadness at the death of human life on earth in a nuclear war, to hope that someday the earth can be reclaimed.

The theme or message is cautionary: it would be a tragedy to destroy life on earth, for the earth is a beautiful place. The other moral is that is important to keep hope alive even in the worst circumstances, even in the "anguish of exile." The survivors on the moon are animated by the hope that one day their descendants can return to earth.

The imagery is vivid, depicting the beauty of the stars and comparing the grimmer landscape of the moon with the remembered beauty of the earth. The moon is a:

jumbled wasteland of craters, mountain ranges, and ravines. The crests of the mountains, catching the low sun, burned like islands of fire in a sea of darkness: and above them the stars still shone as steadfastly as ever.

The earth is described as follows:

It was beautiful, and it called to his heart across the abyss of space. There in that shining crescent were all the wonders that he had never known—the hues of sunset skies, the moaning of the sea on pebbled shores, the patter of falling rain, the unhurried benison of snow.

"If I Forget Thee, O Earth" is a short story by Arthur C. Clarke that was first published in 1951. This was only six years after the United States had used atomic bombs against civilians in the Japanese cities of Hiroshima and Nagasaki. This gave rise to a nuclear arms race between the United States and Soviet Union and a policy known as "Mutually Assured Destruction," in which both countries have enough nuclear weapons to completely annihilate their opponents—and perhaps humanity as a whole.

In Clarke's story, the earth has been made uninhabitable by nuclear war and the characters live in a lunar colony. The main image of the story is that of the beautiful but poisoned Earth seen from the moon. The theme is the power of technology to destroy the world if used unwisely and perhaps to provide some hope of redemption in the hands of a few wise people. The moral is that with nuclear weapons, climate change, and heedless environmental degradation, we now have the potential to make our planet uninhabitable and therefore we need to be very careful not to do so.  

The story shows the earth as uninhabitable. A nuclear war has led to the annihilation of life on the planet. Even from the moon, the earth can be seen “gleaming faintly with an evil phosphorescence.”

The few human survivors have taken refuge on the moon. They will have to stay on the lunar surface for hundreds of years until the effect of the toxic nuclear radiation dies down.

 “The winds and the rains would scour the poisons from the burning lands and carry them to the sea, and in the depths of the sea they would waste their venom until they could harm no living things. Then the great ships that were still waiting here on the silent, dusty plains could lift once more into space, along the road that led to home.”

The story was first published in 1951 during the early years of the Cold War. It reflects the prevailing apprehensions over the possibility of a nuclear war between the two superpowers, the United States and the Soviet Union, and their allies. After the Second World War, both the superpowers began manufacturing nuclear warheads at an unprecedented scale.

In his story, the author Arthur C. Clarke presents a horrifying picture of the earth. It burns day and night on its “funeral pyre." With this story, he sent a very strong message to world leaders. Through his terrifying portrayal of the earth in the aftermath of a possible nuclear war, he warned against the production and use of nuclear warheads.

The lesson is clear. The story strongly discourages applying science and technology to produce weapons of mass destruction. It urges us to work together as the guardians of this unique planet and do all that is possible to preserve its resources. Instead of engaging in a nuclear arms race, every country should sincerely endeavor to keep our planet safe, clean and beautiful.

Though the Cold War has ended, the story is still very relevant. The production of nuclear warheads hasn’t stopped yet. The list of countries considered nuclear powers has been growing. The danger of war looms large across the globe. There are also environmental concerns regarding the safety of the earth. The insensitive exploitation of natural resources and the emission of greenhouse gases threaten the safety of the planet.

The story presents an artistic imagining of a ruined earth. It exhorts us to grow concerned and sensitive towards our planet before it is too late.

"If I Forget Thee Oh Earth..." is a story of the exile of the people of Earth from their home world. Author Arthur C. Clarke uses the title, which is from a verse in the Bible, to compare the exile of the lunar colony from Earth with the exile of the Jews in Babylon from their homeland of Israel. Psalm 137 in the Bible is a poetic lament of the Israelites as they mourn their captivity far from home. The first verse says: "By the rivers of Babylon, there we sat down, yea, we wept, when we remembered Zion." Zion is the Jew's name for Israel. Verses 5 and 6 say:

If I forget thee, O Jerusalem, let my right hand forget her cunning. If I do not remember thee, let my tongue cleave to the roof of my mouth; if I prefer not Jerusalem above my chief joy.

This passage emphasizes the importance of the memory of their homeland to the Jews. In "If I Forget Thee Oh Earth..." the inhabitants of the lunar colony obviously attach a similar importance to remembering the Earth that they left behind. The ten-year-old boy is taken out to view Earth as a sort of coming of age ceremony. Although Earth is devastated and irradiated by nuclear war, their survival in exile depends upon the hope that someday their descendants will be able to return and reclaim the planet they came from.

But unless there was a goal, a future toward which it could work, the Colony would lose the will to live, and neither machines nor skill nor science could save it then.

Just as the ancient Israelites survived their ordeal in Babylon by remembering Jerusalem, the lunar colonists depend upon the memory of Earth to sustain them generation by generation.

That was the dream: and one day, Martin 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.

In the Bible, in the Book of Psalms, there is a line "If I forget thee, O, Jerusalem."  This is in Psalm 137.  It refers to a time when the Israelites were exiled from their homes (to Babylon) and were wishing they could be back home.  It is a way of acknowledging that Jerusalem was their only true home.

In the Clarke story, people have essentially been exiled from Earth.  The title alludes to the Biblical passage and it means that the people up on the Moon are acknowleding that Earth is their real home.  They will yearn to return to Earth for as long as it takes for the planet to stop being radioactive...

The story "If I forget thee, O earth…" is about the grimmest and scariest consequence imaginable in the aftermath of a possible nuclear war on the earth. Published in 1951, the story reflects the fear and anxieties prevalent at the time. After the Second World War, the world had rapidly been polarizing into two groups ~ the U.S. and its allies and the U.S.S.R. and its allies.

The massive destruction wrought by the twin nuclear bombing in the cities of Japan was still fresh in people's memory. During the Cold War, the U.S., the U.S.S.R. and their allies began to produce nuclear warhead at an unprecedented scale, demonstrating their might and superiority.

The third world war seemed imminent. If it happens it would be a nuclear war. What would be its consequences caught the popular imagination of artists, thinkers and philosophers across the world.

This story is an author’s response to this popular imagination regarding the possibility of a massive nuclear war.

The author Arthur C. Clarke imagines the earth to be an uninhabitable planet. The nuclear war has devastated all forms of life on the planet. The earth is still burning with the poisonous radiation. He paints a ghastly image of the earth when seen from the moon:  

"…the portion of the disk (the earth) that should have been in darkness was gleaming faintly with an evil phosphorescence: and he remembered. He was looking upon the funeral pyre of a world—upon the radioactive aftermath…"

The few survivors have built-up a temporary living facility on the lunar surface. They will have to wait there for centuries before they can reclaim the earth. It would happen only when,

“The winds and the rains would scour the poisons from the burning lands and carry them to the sea, and in the depths of the sea they would waste their venom until they could harm no living things.”

Thus the story can be read as a warning to the nations involved in the nuclear arms race. It’s an artist’s urge to the strong and the powerful to create a friendly atmosphere giving away their hostilities.

     The story is set on a lunar colony after a nuclear Armageddon on earth. The simple point of the story is a warning of impending doom if the world doesn't get a handle on the proliferation of nuclear weapons. When the story was written in the 1950s, the threat of atomic weapons was much more on the forefront. 

     However, the point of the story also serves a deeper meaning concerning protecting what we have on earth now. In the story, Father is showing his son the former glory of earth as a motivation for the future and a warning. If we, as parents, fail to protect what we have, whether it be the earth, our culture or family traditions, then our children won't have the same understanding of the world. This is demonstrated by Marvin's inability to understand the nursery rhythm "Twinkle Little Star". To him the stars always shine bright and full because the moon has no atmosphere and he has never experienced life any other way.

     The final message to parents is to introduce our children to the greater glory of our past and encourage them even when all seems lost. There is a need to work for something beyond what we can achieve. Sometimes it is better to show our children than to just tell them.  

This story was first published in 1951. Only six years ago, the world had witnessed the most devastating attack of two atom bombs on two cities of Japan. Following the deadliest Second World War, began an unprecedented competition among the U.S., the U.S.S.R. and their allies to supersede one another in developing nuclear weapons.

This escalation of nuclear arms race made the Third World War seem imminent. If it happens, the destruction would be unimaginable. Some believed it could lead to the annihilation of the mankind. The possibility of the destruction of the whole of our earth captured the imagination of people across the globe.

The main theme of the story echoes this fear of complete annihilation of the human race and the destruction of our beautiful planet.

The author Arthur Charles Clarke imagines a scary picture of our planet in the aftermath of a nuclear war. The earth is devoid any living being and

“… the portion of the disk that should have been in darkness was gleaming faintly with an evil phosphorescence”

This image evokes a scariest image of the earth if there's a  nuclear war. Nobody in the planet would wish to see the earth turn into an inhabitable planet. 

Thus, the story can also be read as a strong warning to stop the futile nuclear arms race. It can also be read as a sincere urge to bring an end to an atmosphere of mutual hostility between powerful nations and replace it with mutual trust and co-operation.

Moreover, the story compels us to stop and appreciate for a while the gifts that the nature and this planet have bestowed upon us:

“the hues of sunset skies, the moaning of the sea on pebbled shores, the patter of falling rain, the unhurried benison of snow,” and “a thousand others.”

We would certainly not like to be in the position of Marvin who had never known and would never know “the wonders” of the shining crescent” that were once the “rightful heritage” of mankind.