According to abbreviated summaries, Eastern Orthodoxy separated from Catholicism when legates of the Pope excommunicated the Patriarch of Constantinople in the year 1054 and were in turn excommunicated by him, thus separating the two churches for the rest of history. Unfortunately, this simple narrative fails on closer inspection. In the first place, the excommunication was invalid according to church law because the authority of the legates was only valid during the Pope’s lifetime, and Pope Leo IX had already died before it took place. Additionally, the Eastern and Western churches were at times in union again (at least nominally) in 1272 and as recently as 1439. On the other hand, substantial divisions between the Greek East and the Latin West had grown for centuries prior to 1054. John Hamer of Toronto Centre Place will look at the history of the Eastern and Western churches and chart history of their division.