To that effect, I'd like to provide my translation of a delightful sermon of St. Augustine in A.D. 408 on the Feast of Pentecost to neophytes (newly-initiated Catholics). The Latin of this sermon was pretty easy to translate (or maybe I'm just getting better at it).
That which you see on the altar, is that which you saw last night: but what it is, what it meant, how great a thing the sacrament contained, you had not yet heard. Now, what you see is bread and a chalice [of wine]; that, indeed, is what your eyes declare to you: but that which your faith asks to be instructed about [is this], the bread is the body of Christ, the chalice [of wine] is the blood of Christ. That was stated quite briefly, which perhaps may suffice for faith: but faith desires instruction. For, as the prophet says, "Unless you have believed, you will not understand." (Isa. 7:9) That is, you could now say to me, "You have taught [us] that we may believe; [now] explain that we may understand!"You can find the Latin of Sermon CCLXXII on page 133 of this PDF.
For instance, into the mind of any one of you might come such a thought as: "We learned whence our Lord Jesus Christ took flesh, of the Virgin Mary. The infant was weaned, nourished, grew up, came to to a youthful age, suffered persecution by the Jews, was hung on the tree [of the Cross], was killed on the tree, was taken down from the tree, was buried, on the third day he rose again, and on the day he willed he ascended into Heaven; his body, lifted up, is there, and from there he will come to judge the living and the dead; there he is now, sitting at the right hand of the Father. How, then, is the bread his body? And the chalice, or rather that which the chalice holds, how is it his blood?"
For just that reason, brethren, such things are called “sacraments” because in them one thing is seen, but another thing is understood. That which is seen has a tangible appearance; that which is understood provides spiritual fruit. Therefore, if you wish to understand the body of Christ, pay attention to the Apostle saying to the faithful, “You, moreover, are the body of Christ, and its members.” (1 Cor. 12:27) If, therefore, you are the body of Christ and its members, your mystery is placed on the Lord’s table: you receive your mystery. To that which you are (or: to that which you eat), you answer “Amen,” and, thus answering, you assent. That is, you hear “The body of Christ,” and you answer “Amen.” Therefore, be a member of the body of Christ, that the “Amen” may be true!
How, then, in the bread? Let us bring nothing here of our own [ideas], but let us continue to listen to that same Apostle who, while speaking of this Sacrament, said: "We, the many, are one bread, one body." (1 Cor. 10:17) Understand and rejoice: unity, truth, piety, love. “One bread” – what is that one bread? It is “the one body” which we the “many” are. Bring this to the forefront of your mind: bread is not made from a single grain, but from many. When you were being exorcised, it is as though you were being ground up. When you were baptized, it is as though you were mixed together [into dough]. When you received the fire of the Holy Spirit, it is as though you were being baked. Be that which you see, and receive that which you are! That is what the Apostle spoke concerning the bread.
Now what we should understand concerning the chalice, even though not said, he has shown well enough. As many grains are mixed into one that it might be the visible appearance of bread, just as if to bring about that which the Holy Scripture says concerning the faithful, “They were one soul and one heart in God” (cf. Acts 4:32), so too with the wine: brethren, recall from what wine is made: many grapes hang in a bunch, but the juice of the grapes is combined into one. Even thus Christ the Lord signified us, willed us to belong to him (cf. John 15:1-8), and consecrated the sacrament of our peace and unity upon his table. Who accepts the sacrament of unity, and keeps not the bond of peace, does not receive the sacrament for his good, but as a testimony against himself!