Raphael, School of Athens, 1509-11. detail, Vatican Museums (3) (48758938333)

In the lower right, Euclid stoops over a slate, using a pair of compasses to explain a theorem to a group of attentive students. Behind him stand Zoroaster holding a celestial globe and Ptolemy holding a terrestrial globe, representing the sciences of astronomy and geography. On the far right edge, the artist Raphael includes his own self-portrait, looking directly at the viewer from behind the astronomers.

This portion of the fresco illustrates the importance of the quadrivium—specifically geometry and astronomy—within the Neoplatonic curriculum of the Renaissance. It visualizes the synthesis of ancient scientific knowledge and its role as a prerequisite for understanding the higher metaphysical truths sought by the philosophers in the center of the mural.