The Commentary of Theodore of Mopsuestia on the Nicene Creed is an important document of an instrumental age in the development of Christianity. Theodore (c. 350-428) was clearly the most important biblical scholar of his age. While his theology eventually led to his loss of favor among some branches of the church, Theodore was at least partially responsible for three church councils held to deal with his ideas, including those of Ephesus and Chalcedon. Mingana has published here, as Woodbrooke Studies 5, for the first time a document that had previously been lost and which contains Theodore's observations on the outcome of the Council of Nicaea, the Nicene Creed.