Mark Shea has an unmatched way of explaining all things Catholic and in this post, he write about how the Sacraments aren't merely symbolic images of grace but vehicles actually delivering substantive grace to the recipient:
To understand this, we need to think of a kiss. A kiss is both physical and spiritual. Through a kiss we give, not merely an invisible reality, nor yet a merely physical gesture without spiritual content, but a sort of combination: an incarnation of love. A kiss is both physical and spiritual, like a human being.
Now sacraments are the kisses of God. Through them God not only symbolizes His love, He enacts it. Something happens to us through sacraments. Something is given. Something of the "stuff" of God is poured ("infused" to use theological technobabble) into the human soul like water into a bucket. Thus, when the Church speaks of grace infused, She speaks of God himself as if He were made of "stuff." In particular, She is recalling us to the language of the Creeds, which describe God himself as a substance when they say that the Three Persons of the Trinity, while distinct, are "one in being." They are made of the same substance, the same "God stuff" if you will.
To many, this seems crude. But then Jesus never shied from "crude" images (like comparing God to a mother hen) if they got His point across. And this is for a very good reason: Jesus Himself is a physical image--the Physical Image--of the ultimate spiritual reality (Hebrews 1:3). He is God in human flesh (John 1:1). And as God in human flesh he both symbolized God and carried to us His very Life--like a sacrament.
Which this leads us directly back to the Catholic image of grace as a "substance." For according to Scripture, the new life of grace is nothing other than the new life of God himself coming to dwell in a human personality. Thus, when the Catholic tradition describes the bestowal of grace as an "infusion" it is being thoroughly biblical, for it is relying directly on what our Lord himself said when He described the new life as "living water" welling up in the soul of the one who believes in him (John 7:38). Elsewhere, he put the same idea a bit differently and promised, "Anyone who loves me will be true to my word, and my Father will love him; we will come to him and make our dwelling place with him" (John 14:23). Or to use an even more shocking biblical image, grace is that "seed" which impregnates our souls with Christ as it impregnated the womb of Mary.
The idea, then, is that grace (that is, the very substance of the Father, Son and Holy Spirit) is something which really enters into our being and radically alters it, generating new life. This is in contrast to the idea held by some Christians that grace is merely a sort of legal fiction by which sinners (who remain objectively bad) are simply declared legally "not guilty" and "covered with Christ's righteousness as snow covers a dunghill." To be sure, we are pardoned by the sacrifice of Christ, but this is the beginning, not the end of the Christian life. The rest of the story, which all believers live every day, is the fact that God causes us to "grow in him" to be changed by an increasing "infusion" of his grace into more and more areas of our being. We don't merely stop being sinners and have the heavenly account books zeroed out so we can squeak into heaven. We start being saints and go from grace to grace and glory to glory.
But why then, since this is all image and metaphor, do we need physical sacraments? What good is all this water and oil and laying on of hands and bread and wine and smells and bells if they are only pointing us to the purely spiritual reality? Why not cut to the chase and avoid all this clumsy paraphernalia?
In a word, says the Church, because we are not disembodied angelic spirits. As God reminds us every time we use the restroom or make love or eat a sandwich, we are a peculiar combination of dreams and bones, part angel and part alley cat. So if sanctity is to really permeate our total being (body, soul and spirit, as Paul points out in 1 Thessalonians 5:23) it must be addressed to our total being. As the child said to his mother, curling up to her side during the lightning storm, he couldn't just pray to God in his spirit because "I needed someone with skin on." So do we. Thus, the grace of God is given to our entire being, not just the spiritual part, in the sacraments which are both physical and spiritual "means of grace." We experience, not just a legal "not guilty," not merely a divine attitude of "unmerited favor," but a physical touch and, through it, power from the grace of God so that we may be like the Man (not the disembodied Ghost) Christ Jesus and love the Lord with all our heart, soul, mind and strength: that is, with our total being.
That is simply beautiful and underscores why the faithful Catholic looks to the sacraments as something to treasure, something to yearn for and seek often, something to expectantly anticipate.
It explains why the faithful Catholic esteems Baptism, Confirmation, Confession, Marriage, the Anointing of the Sick, Holy Orders and the Eucharist.
Each are in essence buckets of grace with which God pours out His love.
It makes me think that we Catholics should be participating in and trumpeting a #GraceBucketChallenge.