Cosmic distances - Aetius '2.31 Diels' and some related texts

In the Doxographi Graeci the preferred short heading of Aet. 2.31 (Greek te xt below, p. 28) is 'On Distances,' though ps.Plutarch has a long heading. This chapter is about the distances of the sun and moon from each other and from the earth (lemmas 1 to 3, in both ps.Plutarch and Stobaeus), and of t he real or apparent shape of the heaven relative to its distance from the e arth (lemmas 4 and 5, Stobaeus only). Parallels from Ioann. Lydus and Theod oret for what is in ps.Plutarch are given by Diels in apparatu. To the best of my knowledge it has not been noticed that a version of ps.Plutarch's te xt is preserved in a scholium on the Almagest, which constitutes our earlie st evidence for the text. The correctness of Diels' reconstruction is quest ionable. Though certainty, naturally, is beyond our reach it is quite possi ble that these two sets of lemmas represent two distinct Aetian(or proto-Ae tian) chapters. These may have been coalesced by Stobaeus (or Aetius), whil e ps.Plutarch abridged the second (or the two final lemmas) away. These con siderations necessitate an inquiry into the parallels that are available, i ncluding material from an introduction to Aratus. The vexing question of sh ort versus long(er) chapter headings is also relevant in this context. Furt hermore, the contrasting views regarding cosmic distances are not only a fe ature of the Placita literature with a distant origin in Aristotle, but als o, apparently, of the commentary literature with a distant origin in Aristo tle, but also, apparently, of the commentary literature on Plato's Timaeus. Arguably in a passage in Plutarch's De facie these two traditions intersec t. Finally, a case can be made out for Eudemus not Theophrastus as an inter mediary source of Presocratic astronomical data in the Placita.