"Somnium" is an essay, or short story by the famous scientist Johannes Kepler. Dating back to 1608 it is considered by quite some people the first Science Fiction story ever written. I an placing a summary here. You will notice that it's technically not yet complete science fictional as it turns out to be "just" a dream. Anyway, here's the contents.

In a wind-wracked chamber, beneath a sky suffused with unseen stars, a lone scholar drifts into uneasy slumber. His mind, restless with questions of the heavens, transports him beyond the familiar realm of Earth and sets him on a voyage that defies both gravity and imagination.

Awakening within his dream, he finds himself greeted by a silent guide—a figure robed in the pale luminescence of distant worlds. This mysterious mentor speaks of the Moon, our steadfast companion in the night sky, not as a barren rock but as a realm of profound marvels. With a solemn invitation, he offers the scholar passage aboard a vessel powered not by wind or oars, but by the subtle currents of celestial forces themselves.

The craft glides from its earthly mooring, surging skyward on invisible wings. As it escapes the bounds of air and atmosphere, the scholar beholds glittering constellations, comets trailing threads of light, and nebulous clouds where stars are born. Each moment of the journey clarifies the stark contrast between the vibrant, ever-changing tapestry of space and the solidity of his terrestrial home.

At last, the Moon looms large before them. Its surface, far from the dull gray the scholar had imagined, is alive with shape and texture—vast plains of shimmering dust, jagged peaks carved by ancient impacts, and craters whose depths swallow half the sky. The guide explains that here, day and night perform an unending duel: a lunar day scorches with relentless brilliance, then yields to a night so frigid it seems to freeze the very air.

They descend upon a vast basin, where undulating dunes of lunar soil shift in silent storms. These tempests, borne not of water but of fine particles set aloft by solar winds, sweep across the landscape with ghostly whispers. The scholar trembles at the sight—and at the knowledge that these winds carry echoes of cosmic history, remnants of asteroids shattered in the darkness beyond.

Wandering onward, they come upon the ruins of an ancient lunar settlement. Stone structures half-buried in dust bear unfamiliar symbols—swirls and lines that hint at an intelligence attuned to forces the scholar cannot fathom. The guide reveals that, in ages past, beings once thrived here—beings who mastered the rhythms of the cosmos, weaving themselves into the cycles of light and shadow. In these silent vestiges, the scholar perceives the triumphs and follies of what might have been: a civilization granted eternity by the Moon’s slow march around its parent world, yet ultimately undone by the same forces they sought to command.

As they traverse cratered plains and scale obsidian ridges, the scholar’s thoughts turn inward. Each new sight challenges his Earth-bound assumptions: that time flows continuously, that heat and cold exist only in narrow bounds, that life must resemble life as he knows it. The Moon’s extremes—its deadly calms and violent upheavals—become metaphors for the vast, untapped potential of the human mind: to endure hardship, to transcend limits, to reimagine the very essence of existence.

When their exploration draws to a close, the guide leads the scholar back to the waiting vessel. Before he steps aboard, the guide places a silvery fragment—a sliver of lunar rock—into the scholar’s hand. “Let this remind you,” he says, “that every boundary you once believed absolute is but a threshold to something greater.”

The voyage home is swift and silent. The starfields dissolve into familiar clouds, the pull of Earth’s gravity draws them back, and soon the scholar finds himself once more in his study, dawn’s first light creeping across his desk. In his hand, he feels the weight of that celestial shard—cold, smooth, impossibly real. The dream recedes like mist, but its lessons persist: that the universe is vast beyond reckoning, that curiosity can carry us to unimaginable heights, and that the Moon, long regarded as a pale enigma, holds within its dust the promise of discovery.

And so, awakened by sunlight rather than starlight, the scholar sets quill to parchment. His heart, charged with the wonder of his lunar odyssey, composes an account not merely of rocks and craters, but of the infinite possibilities that lie awaiting those bold enough to dream.