The Eucharist, Foundation of the Church

"When the Lord calls his body bread, made from the collection of a large number of grains, he is pointing to the unity of our people. And when he calls his blood wine, which is pressed from a large number of clusters of grapes to form a single liquid, he signifies that our flock is made up of a multitude gathered into unity."

Cyprian of Carthage, Letter 69 V,2

"Just as the head and the body constitute a single human being, so Christ and the Church constitute a single whole. This union is effected through the food that he has given us in his desire to show the love he has for us. For this reason he united himself intimately with us. He blended his body with ours like leaven, so that we should become one single entity, as the body is joined to the head."

John Chrysostom, Homily on I Corinthians