Leo states that those who recite the creed profess that they "believe in God the Father Almighty, and in Jesus Christ his only Son our Lord, who was born of the Holy Ghost and the Virgin Mary"; by these three clauses "the engines of almost all heretics are shattered."
Bespeaking the necessity of the Incarnation, he next offers scriptural justification for the dogma and against the position of Eutyches, noting that the latter, for his own illumination on this matter, might have read relevant passages in Matthew, St. Paul's Epistle to the Romans, or Isaiah.
[citation needed] Again invoking the text of the Creed, Pope Leo illustrates the coexistence of human and divine natures in Jesus, also drawing upon references to the New Testament, e.g. "The infancy of the Babe is exhibited by the humiliation of swaddling clothes: the greatness of the Highest is declared by the voices of angels."
[citation needed] The Pope is astonished that the folly of Eutyches has not been more soundly rebuked, and he concludes by asking Flavian's "solicitude...to see that, if by God’s merciful inspiration the case is brought to a satisfactory issue, the inconsiderate and inexperienced man be cleansed also from this pestilent notion of his."
Pleading Christlike mercy on the matter, Leo notes Eutyches's perceived occasional indifference to his heresy, and seems hopeful that the excommunicate will soon recant.