The present work consists in the first critical edition, with French annotated translation, of Sergius of Reš'aynā's adaptation of Alexander of Aphrodisias' treatise On the cosmos. This adaptation had already been translated into Italian, more than eighty years ago, by Giuseppe Furlani, but the Syriac text remained unpublished and survived in a single manuscript. The Greek text is no more extant; only a twice published Arabic version exists, which seems to more reliably represent the original treatise. The notes to the translation are limited to relevant rhetorical and philological problems, or to single points of grammar. © Le Muséon, 2010.