What is daily bread? That for one day.
For because He had said thus, Your will be done in earth as it is in heaven, but was discoursing to men encompassed with flesh, and subject to the necessities of nature, and incapable of the same impassibility with the angels:— while He enjoins the commands to be practised by us also, even as they perform them; He condescends likewise, in what follows, to the infirmity of our nature. Thus, perfection of conduct, says He, I require as great, not however freedom from passions; no, for the tyranny of nature permits it not: for it requires necessary food. But mark, I pray you, how even in things that are bodily, that which is spiritual abounds. For it is neither for riches, nor for delicate living, nor for costly raiment, nor for any other such thing, but for bread only, that He has commanded us to make our prayer. And for daily bread, so as not to take thought for the morrow. Matthew 6:34 Because of this He added, daily bread, that is, bread for one day.
And not even with this expression is He satisfied, but adds another too afterwards, saying, Give us this day; so that we may not, beyond this, wear ourselves out with the care of the following day. For that day, the interval before which you know not whether you shall see, wherefore do you submit to its cares?
This, as He proceeded, he enjoined also more fully, saying, Take no thought for the morrow. He would have us be on every hand unencumbered and winged for flight, yielding just so much to nature as the compulsion of necessity requires of us.