…Consider the divine Word. In the Bible, God creates the whole universe through the power of his word: “Let there be light,” says the Lord, “and there was light” (Gn 1:3). The prophet Isaiah speaks for Yahweh and says, “For just as from the heavens the rain and snow come down and do not return there until they have watered the earth, making it fertile and fruitful… So shall my word be that goes forth from my mouth; It shall not return to me void, but shall do my will, achieving the end for which I sent it” (Is 55:10-11) God’s speech does not so much describe the world as create it and constitute it. In the first chapter I insisted that Jesus is not simply one spiritual teacher among many but the Son of God, the very Logos of God, the Word by which the universe was made. Therefore what Jesus says is “Lazarus, come out!” (Jn 11:43), and he came out; “Little girl, I say to you, arise!” (Mk 5:41), and she got up; “Child, your sins are forgiven” (Mk 2:5), and they are forgiven. The night before he died, Jesus took bread and said, “This is my body, which will be given for you” (Lk 22:19). In the same way, after the meal, he took the cup and said, “This cup is the new covenant in my blood, which will be shed for you” (Lk 22:20). Since Jesus’s word is the divine Word, it is not merely descriptive but transformative. It creates, sustains, and changes reality at the most fundamental level. When at the consecration the priest moves into the mode of first-person quotation, he is not speaking in his own person but in the person of Jesus—and that’s why those words change the elements.
—From Catholicism by Fr. Robert Barron, pp. 191-192