Thisisthefirststudytoassessinitsentiretythefourth-centuryLatincommentaryonPlato’sTimaeusbytheotherwiseunknownCalcidius,alsoaddressingfeaturesofhisLatintranslation.Thefirstpartexaminestheauthorialvoiceofthecommentatorandtheoverallpurposeofthework;thesecondpartprovidesanoverviewofthekeythemes;andthethirdpartreassessesthecommentary’srelationtoStoicism,Aristotle,potentialsources,andtheChristiantradition.ThiscommentarywasoneofthemainchannelsthroughwhichthelegacyofPlatoandGreekphilosophywaspassedontotheChristianLatinWest.Thetext,whichalsoestablishesaconnectionbetweenPlato’scosmologyandGenesis,thusrepresentsadistinctiveculturalencounterbetweentheGreekandtheRomanphilosophicaltraditions,andbetweennon-ChristianandChristiancurrentsofthought.