This letter, written in 430, represents Nestorius’s reply to Cyril’s Second Letter to Nestorius,1 and so marks the first occasion in which the bishop of Constantinople directly set out his views on the topic of the debate to his Alexandrian counterpart. Although it maintains the degree of formality and graciousness expected of such communications, the letter exhibits a striking sarcasm over Cyril’s long-windedness and a clear rebuke to his meddling in the affairs of the church in the imperial capital. The “actions” threatened at the outset of the letter likely refer to Nestorius’s intention to consider the complaints against Cyril brought to him by the persons expelled from Alexandria who had fled to Constantinople for refuge, also referred to in Cyril’s second letter.