The Day, the Month, and the Year: What Plato Expects from Astronomy

The Timaeus apparently assigns a different task to astronomy than that in the educational programme set out in the Republic. There is no word about the reorientation required in the Republic that astronomers should ascend to a post-observational study of
“the real decorations [of the heavens]—the real movements that these move by true
quickness and true slowness in true number and in all true figures in relation to each
other, carrying along the things contained in them, which can be grasped by reason and
thought, and not by sight.” (Republic 529d) Nevertheless, I argue that—albeit with vastly
different theoretical presuppositions about perceptible entities—the Timaeus takes into
consideration some of the strictures of the Republic. Similar to the way the reform of astronomy required in the Republic, only such observational astronomy can pass muster in
the Timaeus whose major aim is to reduce the regularities of the motions of the different
celestial objects to components that are connected to the fundamental motions of the
World Soul. This enterprise can be claimed—within the confines of this likely story—to
integrate in its fully developed form every important intellectual pursuit there is.