Plato and planetary order: Uncertainty in the positions of Mercury and Venus

Abstract

In Plato’s Republic and Timaeus, and in the pseudo-Platonic Epinomis, the author(s) discuss the planetary order for the Moon, Sun, and planets. Based on these works, many ancient, medieval, and modern authors assert without explanation that Plato’s order for the first four planets is Moon-Sun-Venus-Mercury. While this order may have been Plato’s intention, this article presents a differing opinion by claiming that Plato’s words lack sufficient clarity for a reader to understand Plato’s order for Mercury and Venus. This claim has a three-fold basis: (1) Plato’s difficult to understand planetary color ideas in Republic do not uniquely identify the order for Mercury and Venus; (2) Historical accounts of planetary color do not always support Venus being whiter than Mercury—an argument sometimes used for Venus residing below Mercury in Plato’s scheme; (3) Neither Timaeus nor Epinomis clearly state the order for the two planets. The paper concludes with brief conjectures on why Plato remained obscure on planetary order.