• DOI:10.1177/002182869202300401
• Corpus ID: 118643709

Heraclides and Heliocentrism: Texts, Diagrams, and Interpretations

@article{Eastwood1992HeraclidesAH,
  title={Heraclides and Heliocentrism: Texts, Diagrams, and Interpretations},
  author={Bruce Stansfield Eastwood},
  journal={Journal for the History of Astronomy},
  year={1992},
  volume={23},
  pages={233 - 260}
}

• B. Eastwood
• Published 1 November 1992
• Physics
• Journal for the History of Astronomy

For over a century Heraclides of Pontus (4th century B.C.) has stood with Aristarchus of Samos (3rd century B.C.) as one of the ancient precursors of Copernicus. Heraclides is supposed to have advanced not only a hypothesis that the Earth rotates on its axis once a day but also the idea that the Sun as easily as the Earth may be a centre of planetary motion. There is, however, a very simple historical difficulty with this widely assumed view of Heraclides's planetary doctrines. Whereas Copernicus knew of Aristarchus's heliocentrical hypothesis,' neither Copernicus nor Kepler nor anyone else before the nineteenth century put forth the name of Heraclides as an ancient heliocentrist.? In an earlier study I have shown that the texts ofVitruvius, Pliny the Elder, and most especially Macrobius do not preserve any sort of Sun-centred or circumsolar path for either of the planets Mercury and Venus, while there is in the writing of Martianus Capella an unambiguous circumsolar theory for these two inner planets, which Martianus does not ascribe to any authority.' The Capellan theory was recognized by Copernicus and Kepler and all writers on the subject ofheliocentrism since the Renaissance. Where then does the name of Heraclides come from? Only two sources have ever been cited to support the connection of Heraclides's name with a heliocentrical motion. These are Simplicius's commentary on Aristotle's Physics and Calcidius's commentary on Plato's Timaeus. I deal below with both, the first more briefly, the second in full detail. For any serious attempt to find a line of thought from late Antiquity through the Middle Ages to Copernicus, the text ofCalcidius has been the crucial foundation. What I propose to show is that Calcidius's commentary (and incidentally Simplicius's work as well) offers no ground whatever for attributing to Heraclides of Pontus an idea of circumsolar orbits for Mercury and Venus. This idea came into the Middle Ages only through Martianus Capella. No matter what authorities the medievals later looked back to for this notion, Heraclides and the Heraclidean conception identified by Calcidius were never among these sources. We simply have no basis for assigning the idea to any writer in the Latintradition before Martianus Capella, and Heraclides disappears from the picture completely. His name should also be removed from all the modern textbook accounts erroneously associating this circumsolar pattern with a Greek of the fourth century before the Christian era. The name of Aristarchus was likewise not connected with heliocentrism in the Middle Ages, but his widespread recognition in Antiquity and his rediscovery in the Renaissance have secured his position as a forerunner of Copernicus. While no one seriously claims that the medievals knew Aristarchus as a heliocentrist,