Pythagoras, the enigmatic figure whose name is forever intertwined with the famous theorem, emerges from the mists of ancient Greece as a polymath of profound influence. Born around 570 BCE on the sun-kissed isle of Samos, he transcended the bounds of ordinary existence, becoming a philosopher, mathematician, and the founder of the mystical Divine Brotherhood of Pythagoras. Despite the veil of legend cloaking much of his life, his legacy persists through the enduring resonance of the Pythagorean Theorem.

Some of the legends surrounding Pythagoras and his followers are perplexing, such as abstaining from beans and contemplating Earth's celestial doppelgänger and some “of his followers” even ascribing divine status to Pythagoras himself. Yet, they are also said to have tossed him into the sea and left him to die because the Pythagorean theorem was too disruptive.

Historical narratives, as recounted by the Syrian historian Iamblichus, intertwine Pythagoras's journey with encounters with luminaries like Thales of Miletus and Anaximander. His sojourns to Egypt, potential captivity in Babylon, and rumoured voyages to India add layers to the mystique surrounding his life. Eventually, he established a secretive school in Croton, where mathematical revelations were attributed to him for centuries to come. All members took strict vows of secrecy, and all new mathematical results for several centuries were attributed to his name.

While the theorem bearing his name is celebrated as a pinnacle of mathematical discovery, its origins remain obscured by the sands of time. Babylonian tablets dating back to millennia BCE and Indian texts from 800 to 400 BCE, foreshadow its principles, suggesting a broader cultural inheritance. Pythagoras believed fervently in the power of numbers. To him, they weren't just symbols or tools for calculation; they were the very fabric of the universe, the essence of all things. The Pythagoreans declared their motto: “All Is Numbers.” They wanted to figure out how things worked— absent gods with thunderbolts— and everywhere they looked, they found numbers.

The Greeks believed all numbers could be expressed as either a whole number or a ratio of two whole numbers. But the Pythagorean theorem blew a big hole of confusion and chaos, something the Pythagoreans couldn’t deal with; to the Pythagoreans, it was a challenge to their entire worldview, which was built on the supremacy, even divinity, of numbers that did not do such weird things.

There was the tale of Hippasus, a daring disciple who dared to challenge the boundaries of knowledge. It is said that Hippasus stumbled upon the secret of the theorem during his studies. He crafted a right triangle with sides of length 1 and sought to uncover the length of the elusive hypotenuse. What he found shook the very foundations of Pythagorean belief: the hypotenuse was not a simple, rational number. It was irrational, defying the neat ratios of integers and fractions.

When Hippasus shared his discovery with his fellow Pythagoreans, he unleashed a storm of controversy. Pythagoras, aghast at the implications of this newfound irrationality, cast out his once-loyal disciple. For the Pythagorean Theorem wasn't just a mathematical curiosity; it was a challenge to their entire worldview, a testament to the complexity and mystery of the universe. Despite the tumultuous aftermath of its discovery, the Pythagorean Theorem endured. It became a cornerstone of geometry, a beacon of certainty in a sea of mathematical uncertainty. And Pythagoras, in his quest for truth through numbers, left an indelible mark on the annals of human knowledge. So the legend goes, a tale of brilliance and betrayal, of discovery and disillusionment.

Today, the Pythagorean theorem continues to be taught in classrooms worldwide, serving as a testament to the enduring legacy of Pythagoras and his followers. While the historical details surrounding its discovery may be debated, the theorem's enduring relevance and its impact on human understanding of mathematics remain undeniable. Its applications extend far beyond basic geometry, influencing fields like trigonometry, calculus, and even physics.