Having shown how the Eucharist was prefigured in the manna and water given to the Jews in the desert, Ambrose proceeds to strengthen the faith of the Christian who asks, “How can it be Christ, since it only looks like bread and wine?” He appeals to the power of God, who created everything out of nothing, who empowered the prophets by their word to effect wonders in nature, and who caused the Virgin to conceive. From such reminders of God’s power, Ambrose draws his conclusions: the power of Christ is greater than that of any prophet; his blessing consecrates what nature has formed, namely, the bread and wine. Indeed, Christ’s blessing is more powerful than nature itself, since, by his blessing, “the nature of the elements itself is changed”: bread and wine become his Body and Blood. 

Let us therefore everywhere be attentive to God. Let us not contradict him although what he says appears to be contrary to our reasoning and understanding. Thus we carry out in the Mysteries not only what appears to our senses but what his words tell us. For his word is not able to deceive; our senses are easily deceived. Because the Word says, “This is my Body”, let us be attentive, let us believe, let us look upon him with the eyes of the spirit. For Christ did not give us something sensible; even in the sensible things, all is spiritual.