Everything is theoretically impossible, until it is done.

Robert A. Heinlein, dreamer of futures and teller of bold tales, once declared: “Everything is theoretically impossible, until it is done.” These words shine with the fire of defiance, a cry against the chains of doubt and the voices that say, “It cannot be.” For throughout the story of humankind, all great works were once called impossible—until the day they were accomplished. What men of one age sneer at as folly, men of the next age honor as triumph. Heinlein’s wisdom teaches us that impossibility is not a law of nature, but a veil covering what has not yet been achieved.

The ancients themselves lived by this paradox. Who could have imagined that fire could be stolen from the heavens? Yet Prometheus, in myth, brought it down, and mankind was forever changed. To those who first saw the sea stretching beyond the horizon, crossing it seemed impossible; yet men built ships and sailed into the unknown, discovering worlds undreamed of. The impossible is always the shadow that precedes the dawn of human courage. To say “it cannot be done” is to speak too soon, for history is a chronicle of impossibilities made real.

Consider the story of flight. For centuries, man gazed at the birds with envy, strapping wings to his arms in foolish attempts, mocked and broken by the air. Learned men declared heavier-than-air flight impossible, a dream fit only for fables. Yet in 1903, at Kitty Hawk, the Wright brothers rose into the sky, their fragile machine carrying them through the air. What was impossible in theory became fact in practice. The world was never the same, and the sneers of impossibility were silenced by the hum of engines.

So too with the conquest of space. Once, the heavens were untouchable, the domain of gods and stars alone. Learned scholars argued that man could never escape Earth’s gravity, never walk upon another world. Yet in 1969, Neil Armstrong set foot on the Moon, and with his step declared to all generations: the impossible has been done. Heinlein, who wrote of such journeys in fiction, saw with prophetic clarity that impossibility is often nothing more than the ignorance of those who have not yet dared.

But Heinlein’s words are not only for inventors and explorers. They are for every soul who dreams. Each person faces voices—sometimes within, sometimes without—that whisper “you cannot.” A new life, a great endeavor, a bold change—all may seem impossible until the moment they are begun, until courage transforms the unthinkable into reality. What seems like a wall is often only a door waiting to be opened by persistence and daring.

Yet let us be wise: the path to turning the impossible into the possible is not ease but struggle. Every breakthrough is paid for in doubt, failure, and perseverance. The Wright brothers crashed many times; explorers faced storms and starvation; astronauts risked their lives to reach the stars. But these struggles were the price of triumph. The lesson is clear: impossibility is not the end, but the beginning of greatness.

Therefore, children of the future, carry this teaching with you: never bow to the word “impossible.” Hear it, and let it ignite your determination. Ask not “Can it be done?” but “How shall it be done?” Begin where others fear to begin. Work, strive, and persist, for the impossible lasts only until courage rises to meet it. Remember Heinlein’s words, and let them be your banner: everything is theoretically impossible, until it is done. And when you have done it, the world itself will change.