Saint Albert the Great

"Do this in remembrance of me." Two things should be noted here. The first is the command that we should use this sacrament, which is indicated when Jesus says, "Do this." The second is that this sacrament commemorates the Lord's going to death for our sake. 

This sacrament is profitable because it grants remission of sins; it is most useful because it bestows the fullness of grace on us in this life. "The Father of spirits instructs us in what is useful for our sanctification." And his sanctification is in Christ's sacrifice, that is, when he offers himself in this sacrament to the Father for our redemption to us for our use. 

Christ could not have commanded anything more beneficial, for this sacrament is the fruit of the tree of life. Anyone who receives this sacrament with the devotion of sincere faith will never taste death. "It is a tree of life for those who grasp it, and blessed is he who holds it fast. The man who feeds on me shall live on account of me." 

Nor could he have commanded anything more lovable, for this sacrament produces love and union. It is characteristic of the greatest love to give itself as food. "Had not the men of my text exclaimed: Who will feed us with his flesh to satisfy our hunger? as if to say: I have loved them and they have loved me so much that I desire to be within them, and they wish to receive me so that they may become my members. There is no more intimate or more natural means for them to be united to me, and I to them. 

Nor could he have commanded anything which is more like eternal life. Eternal life flows from this sacrament because God with all sweetness pours himself out upon the blessed. 

-- Saint Albert the Great from a commentary on the Gospel of Luke