"Thy will be done in earth, as it is in Heaven."
Behold a most excellent train of thought! in that He bade us indeed long for the things to come, and hasten towards that sojourn; and, till that may be, even while we abide here, so long to be earnest in showing forth the same conversation as those above. For ye must long, saith He, for heaven, and the things in heaven; however, even before heaven, He hath bidden us make the earth a heaven and do and say all things, even while we are continuing in it, as having our conversation there; insomuch that these too should be objects of our prayer to the Lord. For there is nothing to hinder our reaching the perfection of the powers above, because we inhabit the earth; but it is possible even while abiding here, to do all, as though already placed on high. What He saith therefore is this: "As there all things are done without hindrance, and the angels are not partly obedient and partly disobedient, but in all things yield and obey (for He saith, `Mighty in strength, performing His word'); so vouchsafe that we men may not do Thy will by halves, but perform all things as Thou willest."
Seest thou how He hath taught us also to be modest, by making it clear that virtue is not of our endeavors only, but also of the grace from above? And again, He hath enjoined each one of us, who pray, to take upon himself the care of the whole world. For He did not at all say, "Thy will be done" in me, or in us, but everywhere on the earth; so that error may be destroyed, and truth implanted, and all wickedness cast out, and virtue return, and no difference in this respect be henceforth between heaven and earth. "For if this come to pass," saith He, "there will be no difference between things below and above, separated as they are in nature; the earth exhibiting to us another set of angels."
8. "Give us this day our daily bread."
What is "daily bread"? That for one day.
For because He had said thus, "Thy 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," saith 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 thee, 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 hath commanded us to make our prayer. And for "daily bread," so as not to "take thought for the morrow." 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 thou knowest not whether thou shalt see, wherefore dost thou 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.
John Chrysostom (c.347-407): Homily 19 on St. Matthew's Gospel.