Heraclides of Pontus was a Greek philosopher and astronomer of the 4th century BCE. Born in Heraclea Pontica on the Black Sea, he traveled to Athens to study. He was first a student of Pythagorean thinkers before joining Plato’s Academy. According to some ancient accounts, he may have served as temporary head of the Academy during one of Plato’s absences, though this detail is disputed by scholars. After Plato’s death, he is said to have returned to his hometown.

He was a remarkably prolific writer, but none of his works survive complete. Ancient sources indicate he wrote many treatises and dialogues covering ethics, physics, astronomy, music, and literary history. His writings often featured mythological settings and marvellous tales.

Heraclides is historically important for his eclectic ideas, which blended Platonic and Pythagorean thought with scientific speculation. He is particularly noted for an astronomical theory in which he proposed that the Earth rotates daily on its axis while the fixed stars remain still—a view that later influenced other astronomers. In physics, some academics suggest his theory of matter being made of imperceptible “masses” was a precursor to atomism. His literary style and wide-ranging studies made him a significant source for later scholars in philosophy, science, and music theory.