15 Why, then, are our desires scattered over many things, and why, through fear of not praying as we ought, do we ask what we should pray for, and not rather say with the Psalmist: “One thing have I desired of the Lord, that will I seek after: that I may dwell in the house of the Lord all the days of my life, to behold the beauty of the Lord, and to inquire in His temple”? For in the house of the Lord “all the days of life” are not days distinguished by their successively coming and passing away: the beginning of one day is not the end of another; but they are all alike unending in that place where the life which is made up of them has itself no end. In order to our obtaining this true blessed life, He who is Himself the True Blessed Life has taught us to pray, not with much speaking, as if our being heard depended upon the fluency with which we express ourselves, seeing that we are praying to One who, as the Lord tells us, “knows what things we have need of before we ask Him.” Whence it may seem surprising that, although He has forbidden “much speaking,” He who knows before we ask Him what things we need has nevertheless given us exhortation to prayer in such words as these: “Men ought always to pray and not to faint;” setting before us the case of a widow, who, desiring to have justice done to her against her adversary, did by her persevering entreaties persuade an unjust judge to listen to her, not moved by a regard either to justice or to mercy, but overcome by her wearisome importunity; in order that we might be admonished how much more certainly the Lord God, who is merciful and just, gives ear to us praying continually to Him, when this widow, by her unremitting supplication, prevailed over the indifference of an unjust and wicked judge, and how willingly and benignantly He fulfils the good desires of those whom He knows to have forgiven others their trespasses, when this suppliant, though seeking vengeance upon her adversary, obtained her desire. A similar lesson the Lord gives in the parable of the man to whom a friend in his journey had come, and who, having nothing to set before him, desired to borrow from another friend three loaves (in which, perhaps, there is a figure of the Trinity of persons of one substance), and finding him already along with his household asleep, succeeded by very urgent and importunate entreaties in rousing him up, so that he gave him as many as he needed, being moved rather by a wish to avoid further annoyance than by benevolent thoughts: from which the Lord would have us understand that, if even one who was asleep is constrained to give, even in spite of himself, after being disturbed in his sleep by the person who asks of him, how much more kindly will He give who never sleeps, and who rouses us from sleep that we may ask from Him.
16. With the same design He added: “Ask, and you shall receive; seek, and you shall find; knock, and it shall be opened unto you: for every one that asks receives; and he that seeks finds; and to him that knocks it shall be opened. If a son shall ask bread of any of you that is a father, will he give him a stone? Or if he ask a fish, will he for a fish give him a serpent? Or if he shall ask an egg, will he offer him a scorpion? If you then, being evil, know how to give good gifts unto your children, how much more shall your heavenly Father give good things to them that ask Him?” We have here what corresponds to those three things which the apostle commends: faith is signified by the fish, either on account of the element of water used in baptism, or because it remains unharmed amid the tempestuous waves of this world—contrasted with which is the serpent, that with poisonous deceit persuaded man to disbelieve God; hope is signified by the egg, because the life of the young bird is not yet in it, but is to be— is not seen, but hoped for, because “hope which is seen is not hope,” — contrasted with which is the scorpion, for the man who hopes for eternal life forgets the things which are behind, and reaches forth to the things which are before, for to him it is dangerous to look back; but the scorpion is to be guarded against on account of what it has in its tail, namely, a sharp and venomous sting; charity, is signified by bread, for “the greatest of these is charity,” and bread surpasses all other kinds of food in usefulness—contrasted with which is a stone, because hard hearts refuse to exercise charity. Whether this be the meaning of these symbols, or some other more suitable be found, it is at least certain that He who knows how to give good gifts to His children urges us to “ask and seek and knock.”
17. Why this should be done by Him who “before we ask Him knows what things we have need of,” might perplex our minds, if we did not understand that the Lord our God requires us to ask not that thereby our wish may be intimated to Him, for to Him it cannot be unknown, but in order that by prayer there may be exercised in us by supplications that desire by which we may receive what He prepares to bestow. His gifts are very great, but we are small and straitened in our capacity of receiving. Wherefore it is said to us: Be enlarged, not bearing the yoke along with unbelievers. For, in proportion to the simplicity of our faith, the firmness of our hope, and the ardour of our desire, will we more largely receive of that which is immensely great; which “eye has not seen,” for it is not colour; which “the ear has not heard,” for it is not sound; and which has not ascended into the heart of man, for the heart of man must ascend to it.
Source: Letters (New Advent)