Mystery School · Croton · c.530–450 BCE · Communal Order

The Pythagorean Brotherhood

A community that held property in common, imposed five years of silence on new initiates, forbade eating beans, and quietly discovered that musical harmony and the structure of the cosmos both obey the same simple ratios of number — until it was burned out of existence by the very city it had come to dominate.

Almost nothing about Pythagoras survives from his own lifetime. The two substantial biographies that shape most modern accounts — by Porphyry and Iamblichus — were written more than seven hundred years after his death, drawing on a long oral and legendary tradition that had ample time to embellish. This reference separates what is plausibly historical from what is clearly later legend, and is honest about the many places where the two cannot be fully untangled.

Section 01

From Croton to the Fire

Around 530 BCE, a philosopher and mystic named Pythagoras left his native island of Samos — reportedly to escape the tyranny of the ruler Polycrates — and settled in Croton, a prosperous Greek colony on the southern coast of Italy. There he founded a community that was, at once, a religious brotherhood, a philosophical school, and — before long — a genuine political force in the city's affairs.

The community's early decades were remarkably successful. Croton's leading families sent their sons to study under Pythagoras, and the brotherhood's disciplined, communal way of life became closely associated with the city's own civic order and even its military fortunes — Croton's dramatic victory over the neighbouring city of Sybaris around 510 BCE is traditionally linked to Pythagorean influence over the city's government.

That very success created the conditions for its downfall. As the brotherhood's political influence grew, resentment grew alongside it — particularly among Croton's aristocratic families who felt excluded from its inner circle. Tradition names a wealthy Crotonian, Cylon, rejected for membership, as the figure who organised the backlash that would ultimately destroy the community.

c.570 BCE
Birth on Samos
Pythagoras is born on the Greek island of Samos. Later legendary biographies claim extensive travels to Egypt and Babylon in his youth, though these journeys cannot be independently confirmed.
c.530 BCE
Arrival at Croton
Pythagoras settles in the Greek colony of Croton in southern Italy and begins gathering followers, founding a communal school of philosophy and religious practice.
c.510 BCE
Victory over Sybaris
Croton defeats the rival city of Sybaris. Pythagorean influence over Croton's government is at its height, and the brotherhood's political power is now substantial.
c.508–494 BCE
Cylon's Rejection
Cylon, a wealthy Crotonian, is refused admission to the brotherhood. Tradition holds he organised political opposition that would eventually turn violent.
c.500–494 BCE
The Meeting House Burns
A mob attacks a gathering of Pythagoreans, reportedly setting fire to the house where they were meeting. Many members are killed; accounts differ on whether Pythagoras himself died in the attack or escaped.
c.494 BCE
Death at Metapontum
The more widely credited tradition holds that Pythagoras fled to nearby Metapontum, where he died shortly afterward — though even this account rests on later, uncertain sources.
5th century BCE onward
Diaspora & Survival
Surviving members scatter across the Greek world, carrying Pythagorean ideas about number, harmony and the soul into the wider philosophical tradition that would eventually shape Plato.
Section 02

Life Inside the Community

The Pythagorean community at Croton was organised as a koinobion — a communal household in which property was held in common rather than individually owned, an arrangement genuinely unusual for the ancient Greek world and one that later monastic Christian communities would echo, whether directly influenced or not.

New members reportedly underwent a demanding initiation: a period of silence lasting up to five years, during which candidates listened to teachings without speaking and, according to tradition, without even seeing Pythagoras directly — proving their discipline and commitment before being admitted to fuller participation. The community is traditionally described as splitting into two tiers: the akousmatikoi ("those who listen"), who received teachings as unexplained maxims to be obeyed on trust, and the mathematikoi ("those who learn"), who were given the reasoning and mathematical demonstration behind the doctrine.

Unusually for the period, the community is said to have admitted women as full members. Theano, traditionally identified as Pythagoras's wife, is credited in later sources with philosophical writings of her own and, in some accounts, with leading the community after Pythagoras's death — though as with much else here, the historical record is thin and largely reconstructed from centuries-later testimony.

Members practised vegetarianism, held strict secrecy about the community's teachings, and swore not to reveal what they learned to outsiders — a discipline of silence significant enough that later Greek writers used "Pythagorean silence" as a byword for absolute discretion.

Section 03

The Akousmata — Rules of Life

The akousmata were short, cryptic maxims given to new members without explanation — obeyed first, understood later, if at all. Later Pythagoreans and biographers like Iamblichus offered symbolic readings of maxims that may originally have had far more mundane, practical origins. What follows assesses the best-known examples.

Abstain from Beans
Practical Origin Likely
The most famous Pythagorean taboo. Ancient sources offer mystical explanations (beans resembled testicles, or contained departed souls); modern scholars have proposed favism — a genetic sensitivity to fava beans common in Mediterranean populations, causing serious illness in susceptible people — as a plausible practical origin later wrapped in symbolic meaning.
Do Not Stir the Fire with a Knife
Symbolic (per Iamblichus)
Interpreted by later Pythagoreans as a warning against provoking the anger of powerful people. Whether the original maxim carried this meaning or a more literal domestic caution is unknown.
Do Not Break Bread
Symbolic (per Iamblichus)
Read as an injunction against dividing what should unite people — friendship, community, shared purpose — rather than a literal rule about meals.
Wear White Garments
Plausibly Literal
Associated with ritual purity, a concern shared with several other Greek religious and mystery traditions of the period — one of the less contested and more straightforwardly religious of the maxims.
Efface the Mark of a Pot in the Ashes
Symbolic (per Iamblichus)
Interpreted as counsel against leaving traces of anger behind — removing the impression before it can harden into a lasting grudge.
Do Not Travel the Main Roads
Symbolic (per Iamblichus)
Read as advice to avoid following popular opinion uncritically, preferring one's own carefully reasoned path — a fitting maxim for a school built around independent inquiry into number and nature.
Section 04

All Is Number

The Pythagoreans' most consequential and enduring idea is deceptively simple: that number is the fundamental substance of reality — not merely a tool for counting things, but the underlying structure of the cosmos itself, expressed in music, in geometry, and in the movements of the heavens alike.

The community's central symbol, the tetraktys, expressed this conviction in physical form: ten dots arranged in a triangle, four rows deep (1, then 2, then 3, then 4, summing to ten), representing the whole of number and, by extension, the whole of the cosmos. Pythagoreans reportedly swore their most solemn oaths not by the gods directly but by the one "who gave to our generation the tetraktys, which contains the fount and root of eternal nature."

This conviction found its most concrete expression in the discovery that musical harmony corresponds to simple numerical ratios — that an octave sounds when a string is halved (a 2:1 ratio), a perfect fifth at a 3:2 ratio, a perfect fourth at 4:3. Later legend (recorded by Nicomachus) attributes this discovery to Pythagoras noticing harmonious tones from hammers of different weights striking an anvil in a blacksmith's shop — a charming story that is physically impossible, since pitch does not scale with hammer weight in the way the story requires. The genuine underlying discovery almost certainly came from experiments with string length on a simple instrument, the monochord — but the mathematical insight itself, that harmony obeys number, is real and became foundational to the later Western study of acoustics.

From this insight the Pythagoreans extended their reasoning outward to the heavens themselves, proposing that the planets and stars, in their orbits, produced a cosmic harmony — the musica universalis, or "music of the spheres" — inaudible to ordinary human ears but genuinely present in the mathematical structure of the universe. This idea would echo for two thousand years, surfacing again in the work of Johannes Kepler, who titled his own 1619 treatise on planetary motion Harmonices Mundi — "The Harmony of the World" — in direct homage to Pythagorean cosmology.

Section 05

Fact vs Legend

Legend
Pythagoras personally discovered the Pythagorean theorem (a² + b² = c²).
Reality
Babylonian and Indian mathematicians knew and applied this relationship over a thousand years before Pythagoras was born. The theorem carries his name because later Greek tradition credited him or his school with a general geometric proof — not with discovering the underlying relationship itself.
Legend
Pythagoras had a golden thigh, proof of his semi-divine nature.
Reality
This claim appears only in Iamblichus, writing roughly eight centuries after Pythagoras's death, describing events allegedly witnessed by others long before. It has no earlier or independent corroboration and is best treated as devotional legend rather than history.
Legend
Pythagoras studied for years with priests in Egypt and Babylon before founding his school.
Reality
These extensive travels appear in later biographical accounts and cannot be independently verified from earlier or contemporary sources. They may reflect genuine tradition, later invention to lend the school foreign authority, or some mixture of both.
Legend
We possess Pythagoras's own writings explaining his philosophy.
Reality
Pythagoras is traditionally held to have written nothing down at all, teaching entirely through oral instruction. Everything attributed to him survives only through later followers and biographers — the fullest accounts appearing more than seven hundred years after his death.
Legend
"He himself said it" (ipse dixit) shows Pythagorean teaching relied on blind obedience rather than reasoning.
Reality
The phrase genuinely describes how the akousmatikoi tier received unexplained maxims on trust — but the community's other tier, the mathematikoi, engaged in genuine mathematical demonstration and proof. The "blind faith" caricature captures only half the school's actual practice.
Essential Reading
Walter Burkert's Lore and Science in Ancient Pythagoreanism is the standard critical scholarly account, sceptical of the later legendary accretions. Iamblichus's On the Pythagorean Life (translated by Gillian Clark) and Porphyry's Life of Pythagoras are the two major ancient biographies — read as devotional tradition rather than straightforward history.
The Seven-Century Gap
Porphyry and Iamblichus, our two fullest sources, wrote in the 3rd century CE — roughly seven hundred years after Pythagoras's death in the early 5th century BCE. This gap is comparable to writing a detailed, confident biography of a medieval figure today based only on oral tradition. Treat specific anecdotes accordingly.
Connections
The Pythagorean Brotherhood connects to Numerology (its most direct modern descendant), Sacred Geometry (the tetraktys and harmonic ratios), Greek Mystery Schools (contemporary initiatory traditions), and Freemasonry (later Western fraternal orders that absorbed Pythagorean number symbolism into their own ritual systems).