The present study partly supports, partly corrects, and partly complements recent discussions of Arius Didymus fr. 23 and fr. 25 Diels, Aetius I, 20, 1 and Sextus Empiricus AM X, 3-4 = PH III, 124. It proposes a comprehensive interpretation of the first text (A.I), defends the attribution of its content to Zeno of Citium (A.II), interprets the Stoic definitions of space, place and void to be found in the other sources (B.I) and again vindicates the attribution of the core definitions to Zeno (B.II). The central methodological principle is the presumption of innocence for sources.The main conclusions of (A) are: 1. Arius Didymus' fr. 23 deals only with the coherence and the structure of the cosmos, not with its immobility; 2. The coherence of the cosmos, as that of any object, is determined by its hexis which pushes its parts towards its centre; 3. The structure of the cosmos, its stratification into the four concentric spheres of the elements, is determined by the combined effect of (a) the thrust downwards they all undergo from the cosmos' hexis; (b) their own natural weight or lightness and (c) the relative quantitative values of these weights or lightnesses; 4. The reasons adduced against Zeno's authorship are not based on the evidence but on the now prevalent disparaging sceptical approach towards Stobaeus' way of excerpting from Arius.The main conclusions of (B) are: 1. There is no deep contradiction between the various de finitions of space ascribed by our sources to Zeno, Chrysippus and the Stoics in general: what Chrysippus denied was the form of the de finition attributed to Zeno by Aetius, not the concept de fined, even though this form seems to have prevailed later in the school; 2. There is no good reason therefore to question its ascription to Zeno as some modern researchers have done; 3. Here again the error is due to a predominantly sceptical approach towards the reliability of our sources.