Mark of Ephesus is celebrated in Eastern Orthodoxy for resisting reunion with Rome. But a fifteenth-century account describes him dying while vomiting fecal matter. At the end of Vindicating the Filioque, Fr. Thomas Crean asks whether this terrible end carried a particular significance for Catholics. He quotes Joseph Plousiadenos, the bishop of Methone, who contrasts Mark’s death with that of Patriarch Joseph II. According to Plousiadenos, Joseph embraced union with Rome and died giving thanks to God. Addressing the deceased Mark, he writes: “But you, who so insolently abuse him and those who were with him, did not so die, but rather, you breathed forth your soul along with the filth of the latrine. The whole city knows it. For the justice of God knows how to pay back each one for the faith which he has, just as once happened with Arius, that byword for madness. For he sent forth his bowels beneath him, while you expelled the filth upwards.” Those are severe words. Plousiadenos supported union with Rome, and his account is openly polemical. Crean’s footnote also cites a similar description by Ubertin Pusculo, an Italian whom Crean identifies as having been in Constantinople at the time. That deserves historical examination. The medical detail is plausible. Copremesis, or fecal vomiting, is a recognized phenomenon. It can occur with severe intestinal obstruction, and fatal cases involving feculent vomiting are documented in the medical literature. Its existence establishes that such an account is medically possible; assessing the historical sources remains a separate question. So what is the significance Crean sees? The Filioque concerns the Holy Spirit’s eternal procession from the Father and the Son. Crean invokes St. Anastasius I of Antioch’s interpretation of the Psalm’s phrase “breath of his mouth”: the Spirit is the breath, and the divine “mouth” represents the only-begotten Son. If the account is accurate, the symbolism is disturbing. Mark denied that the Holy Spirit proceeds from the Son, the divine “mouth.” His own mouth reportedly became the means by which he expelled filth as he died. Crean closes with this question: “Is it possible to see in this wretched end of Mark Eugenikos, notorious throughout Constantinople, a sign of heaven’s displeasure with one who had so determinedly denied to the divine mouth the honor of breathing forth the consubstantial Spirit, and who has passed on this denial to his posterity?” —Fr. Thomas Crean, Vindicating the Filioque, pp. 428–429.