Pythagoras

Pythagoras (c. 570–495 BCE) was a Greek philosopher and religious teacher born on the island of Samos who, after travels traditionally said to include Egypt, settled at Croton in southern Italy and founded a tightly organized brotherhood devoted to philosophy, mathematics, music, and a disciplined way of life.

Because the Pythagoreans held their teachings in secret and Pythagoras himself left no writings, his historical figure is inseparable from later legend, but the school he established exerted a profound and lasting influence on Greek thought, most visibly upon Plato.

(Note: his tradition is tagged neoplatonism as the closest available family, though he is equally hermeticism-adjacent through the later number-mysticism and correspondence traditions.) For the mind-power lineage, Pythagoras stands for the conviction that reality is structured by number and harmony—that the cosmos is an ordered, intelligible whole whose patterns can be grasped mathematically and musically, the “harmony of the spheres.” This made the deep structure of the world something mind-like and mathematical rather than brute and material.

The Pythagoreans also taught the transmigration of souls (metempsychosis), the immortal soul passing through successive lives, and pursued purification of the soul as the aim of their discipline. Both ideas—reality as harmonious mental order, and the soul as an immortal traveler to be purified—fed directly into Platonism and from there into the entire Western esoteric and mind-power inheritance.