Raphael, School of Athens, 1509-11. detail, Vatican Museums (9) (48759433042)

In the lower-left foreground of the fresco, Pythagoras is shown recording his observations while surrounded by observers, including the philosopher Averroes who leans over him in a white turban. A tablet held by a young man displays the Greek names for musical intervals—Diatessaron, Diapente, and Diapason—and a triangular arrangement of numbers known as the tetraktys. The figures are rendered with heavy drapery and focused expressions, emphasizing the intellectual intensity of the Pythagorean school.

Pythagoras represents the mathematical and harmonic foundations of the universe, a central concept in Renaissance Neoplatonism and the Western esoteric tradition. The presence of the tetraktys on the tablet symbolizes the decad and the harmony of the spheres, ideas that influenced Hermetic thought and the sacred geometry of the early modern period.