Dutch polymath Christiaan Huygens publishes his book Treatise on Light. The book is considered a pioneering work of theoretical and mathematical physics

It Happened on
December 25, 1690

On this brilliant morning of December 25, 1690 in the Republic of Letters, Christiaan Huygens—watchmaker of the cosmos and part-time philosopher of the invisible—released into the world a manuscript so fine, so daring, that even the beams of sunlight paused at his windowsill to eavesdrop.

“Traité de la Lumière” was not merely a book—it was a love letter to the wave, a serenade to the very motion of brightness.

With the precision of a man who had once timed Saturn’s moons, Huygens dared to whisper: “Light… moves like ripples upon a pond. It spreads. It dances. It caresses.”

While others saw rays as little arrows flung from the sun, he saw music. He saw interference, harmony, and motion itself composing the face of reality.

And so, in the flick of a quill, Christiaan Huygens became the choreographer of the invisible—a man who looked into the mystery of light and said, “You are not chaos. You are a wave.”

Historians would later call it physics.
But we know the truth: it was poetry in a lab coat.

Nine months later were born…