“When the fire of God's love has cleansed a man of all unlikeness to God, and such a man receives the Blessed Sacrament, he loses himself in God’s divinity. This is what our Lord told St. Augustine: “I am the food for grown men. Grow and feed on Me. Instead of transforming Me into yourself, you will be transformed into Me.” But, children, before this can happen your natures have to die many a death and we must travel along many a rough and unknown path, along which God draws us, teaching us to die.
Dear children, what a noble, fruitful, wonderful, joyful life is born in this dying! What a noble, pure and immeasurably good thing it is to know how to die! You can see clearly, my dear children, that all the earthly nourishment which we take, bread, wine, everything that we consume, must all perish and be completely transformed before It can be absorbed into our being and united with us. . . .
When such food has been absorbed into us, it has become so unlike itself that no eye, however keen, no understanding could see that it used to be food. It has become so utterly transformed that no man's brain can discover where and how the change has taken place. We can believe it, but we cannot understand it. It is even more impossible to understand and follow the process by which the soul is transformed in union with God, losing its own self so that no reason could grasp that this used to be the soul of a created being.”
(From Spiritual Conferences - The Blessed Sacrament by Johann Tauler, O.P.)