This letter was delivered by a delegation of four Egyptian bishops to Nestorius in his residence after the morning service in Constantinople on Sunday, November 30, 430. Cyril had spent the past year building a solid coalition of support for his case against the bishop of the Eastern capital, by sending letters to various bishops in the East, and, most importantly, by sending to Rome a dossier including extracts from Nestorius’s sermons. After ordering the archdeacon Leo (the future pope) to undertake an investigation, Pope Celestine called a synod to meet in Rome in August, which condemned Nestorius’s teaching. He then wrote to Cyril deputizing him to order Nestorius to retract his errors and embrace the common faith of Rome and Alexandria, while leaving somewhat vague the precise contours of this common faith. In November Cyril thus held his own synod in Alexandria that likewise condemned Nestorius’s views and produced the following letter, intended to spell out in greater detail the Christological dogmas to which the bishop of Constantinople must adhere.