In the region of Tolosa blessed Anthony, having vehemently argued with a hardened heretic about the redeeming sacrament of the Eucharist, had nearly convinced and attracted him to the Catholic faith, except that, after many arguments in which he tried to back out, he added these words:
"Let's cut the chat and come to the facts. If you, Anthony, can prove with a miracle that in the Eucharist of believers there is, however hidden it may be, the true body of Christ, I will renounce every heresy and submit myself to the Catholic faith".
The Lord's servant replied with great faith: "I trust in my saviour Jesus Christ that, for your conversion and for that of others, thanks to His mercy I will obtain what you ask". The heretic stood up and, asking for silence with a gesture of his hand, said: "I'll keep my beast of burden locked up for three days and I will starve him. After three days, in the presence of other people, I'll let him out and I'll show him some prepared fodder. You, on the other hand will show him what you believe to be the body of Christ. If the starving animal, ignoring the fodder, rushes to adore his God, I will sincerely believe in the faith of the Church". The saint agreed straight away. The heretic then exclaimed: "Listen well, everyone!".
Why delay with many words? The day of the challenge arrived. people arrived from far and wide and filled up the square. Christ's servant, Anthony, was present surrounded by a crowd of faithful. The heretic too, with a number of his accomplices. God's servant entered a nearby chapel, to perform the rites of the Mass with great devotion. Once finished, he exited where the people were waiting, carrying reverently the body of the Lord. The hungry mule was led out of the stall, and shown appetising food.
Finally, asking for silence the man of God said to the animal with great faith: "In the name of virtue and the Creator, who I, although unworthy, am carrying in my hands, I ask you, o beast, and I order to come closer quickly and with humility and to show just veneration, so that the malevolent heretics will learn from this gesture that every creature is subject to the Lord, as held in the hands with priestly dignity on the altar". God's servant had hardly finished speaking, when the animal, ignoring the fodder, knelt down and lowered his head to the floor, thus genuflecting before the living sacrament of the body of Christ.
The faithful were filled with uncontrollable joy, the heretics and non-believers were filled with sadness and humiliation. God was praised and blessed, the Catholic faith was honoured and exalted; heretical depravity was shamed and condemned with everlasting insults. The heretic, renounced the his doctrine in front of all present, and from then on was obedient to the precepts of the holy Church (Benignitas 16,6-17).