5 There follows next, “Give us this day our daily bread.” It may be understood simply that we pour forth this prayer for daily sustenance, that we may have abundance: or if not that, that we may have no want. Now he said “daily,” for as long as it is called “today.” Daily we live, and daily rise, and are daily fed, and daily hunger. May He then give us daily bread. Why did He not say “covering” too, for the support of our life is in meat and drink, our covering in raiment and lodging.
Man should desire nothing more than these. Forasmuch as the Apostle says, “We brought nothing into this world, neither can we carry anything out: having food and covering, let us be therewith content.” Perish covetousness, and nature is rich. Therefore if this prayer have reference to our daily sustenance, since this is a good understanding of the words, “Give us this day our daily bread;” let us not marvel, if under the name of bread other necessary things are also understood.
As when Joseph invited his brethren, “These men,” says he, “will eat bread with me today.” Why, were they to eat bread only? No, but in the mention of bread only, all the rest was understood. So when we pray for daily bread, we ask for whatever is necessary for us in earth for our bodies' sake. But what says the Lord Jesus? “Seek ye first the kingdom of God and His righteousness, and all these things shall be added unto you.” Again, this is a very good sense of, “Give us this day our daily bread,” your Eucharist, our daily food.
For the faithful know what they receive, and good for them it is to receive that daily bread which is necessary for this time present. They pray then for themselves, that they may become good, that they may persevere in goodness, and faith, and a holy life. This do they wish, this they pray for; for if they persevere not in this good life, they will be separated from that Bread. Therefore, “Give us this day our daily bread.” What is this? Let us live so,that we be not separated from Your altar.
Again, the Word of God which is laid open to us, and in a manner broken day by day, is “daily bread.” And as our bodies hunger after that other, so do our souls after this bread. And so we both ask for this bread simply, and whatsoever is in this life needful both for our souls and bodies, is included in “daily bread.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)