In the previous paragraph Augustine had spoken of the Apostles as “arrows in the hand of a mighty one” who launches them on their worldwide mission of evangelizing. It is to them that he believes the Psalmist is referring when he writes:
“Blessed is the one who fulfills his desire from them” (Ps 127:5). Well, who is it that fulfills his desire from them [i.e., from the Apostles]? Anyone who does not love the world. A person who is full of desire for the world has no place for what they preached to enter. Throw away what you’re carrying and you’ll have room for what you don’t have. Do you desire wealth? You can’t fulfill your desire from what the Apostles preached. Do you desire honors on earth? You desire what God has given even to beasts, that is, temporal pleasure and bodily health and other such things, and you will not fulfill your desire from them. But if your desire is like that of the deer who desires sources of water (Ps 51:2), if you say, “My soul faints with longing for the courts of the Lord” (Ps 83:3), you fulfill your desire from them, not because they can fulfill such a desire, but because by imitating the Apostles you come to the one who fulfilled their desire. (EnPs 126, 12; PL 37, 1676)
I’ve heard the same point made in similar language: If you come to God with your hands full, you can’t receive what he wishes to give you.