Defence of the Nicene Definition (De Decretis)

A friend who had been arguing with Arians asked Athanasius what the council had done and why it had gone beyond the words of Scripture. Athanasius answered with this letter. Its editor in the Nicene and Post-Nicene Fathers dates it between his return to Alexandria in 346 and his flight in 356, that is twenty to thirty years after the council.

Athanasius describes how the bishops tried one scriptural phrase after another and found that the supporters of Arius could accept each in their own sense, and how the words “from the essence” and “one in essence” were chosen to exclude this (19–20). He gives the number of bishops as “three hundred more or less” (3). The account is that of a committed party, written to defend the council against its critics, and long after the event. At the end Athanasius attaches the letter that Eusebius of Caesarea wrote to his own church from Nicaea, a report written at the time of the council, which quotes the creed in full.