17 Nevertheless, to me here another sense also occurs, if I mistake not, to be preferred; understanding by cleri the inheritances themselves: so that, whereas the inheritance of the Old Testament, although in a shadow significant of the future, is earthly felicity; but the inheritance of the New Testament is everlasting immortality; to “sleep in the midst of the lots” is not too earnestly now to seek the former, and still patiently to look for the latter....And because so well they have slept, on them, as it were on wings now flies, and with praises is exalted, the Church: to wit, the Dove silvered, in order that by this fame of theirs, posterity having been invited to imitate them, while in like manner the rest also sleep, there may be added wings whereby even unto the end of the world sublimely she may be preached.
18. “While He that is above the heavens distinguishes kings over Her, with snow they shall be made white in Selmon”. While He “above the heavens,” He that ascended over all heavens that He might fulfil all things, “while He distinguishes kings over Her,” that is, over that same “Dove silvered.” For the Apostle continues and says, and “He has Himself given some for Apostles, and some Prophets, and some Evangelists, and some Pastors and Teachers.” For what other reason is there to distinguish kings over Her, save for the work of the Ministry, for the edification of the Body of Christ: when she is indeed Herself the Body of Christ? But they are called kings from ruling: and what more than the lusts of the flesh, that sin may not reign in their mortal body to obey the desires thereof, that they yield not their members instruments of iniquity unto sin, but yield themselves to God, as though from the dead living, and their members instruments of righteousness to God? For thus shall the kings be distinguished from foreigners, because they draw not the yoke with unbelievers: secondly, in a peaceful manner being distinguished from one another by their proper gifts. For not all are Apostles, or all Prophets, or all Teachers, or all have gifts of healings, or all with tongues do speak, or all interpret. “But all these things works one and the same Spirit, dividing proper gifts to each one as He wills.” In giving which Spirit He that is above the Heavens distinguishes kings over the Dove silvered. Of which Holy Spirit, when, sent to His Mother full of grace, the Angel was speaking, to her enquiring in what manner it could come to pass that she was announced as going to bear, seeing she knew not a man:...he says, “The Holy Spirit shall come over upon you, and the virtue of the Most Highest shall overshadow you,” that is, shall make a shadow for you, “wherefore that Holy Thing which shall be born of you, shall be called the Son of God.” That “shadow” again is understood of a defence against the heat of carnal lusts: whence not in carnal concupiscence, but in spiritual belief, the Virgin conceived Christ. But the shadow consists of light and body: and further, The “Word” that “was in the beginning,” that true Light, in order that a noonday shadow might be made for us; “the Word,” I say, “was made Flesh, and dwelled in us.”...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)