1 We have undertaken the exposition of a Psalm corresponding to your own “longings,” on which we propose to speak to you. For the Psalm itself begins with a certain pious “longing;” and he who sings so, says, “Like as the hart desires the water-brooks, so longs my soul after You, O God”. Who is it then that says this? It is ourselves, if we be but willing! And why ask, who it is other than yourself, when it is in your power to be the thing which you are asking about?
It is not however one individual, but it is “One Body;” but “Christ's Body is the Church.” Such “longing” indeed is not found in all who enter the Church: let all however who have “tasted” the sweetness “of the Lord,” and who own in Christ that for which they have a relish, think that they are not the only ones; but that there are such seeds scattered throughout “the field” of the Lord, this whole earth: and that there is a certain Christian unity, whose voice thus speaks, “Like as the hart desires the water-brooks, so longs my soul after You, O God.”
And indeed it is not ill understood as the cry of those, who being as yet Catechumens, are hastening to the grace of the holy Font. On which account too this Psalm is ordinarily chanted on those occasions, that they may long for the Fountain of remission of sins, even “as the hart for the water-brooks.” Let this be allowed; and this meaning retain its place in the Church; a place both truthful and sanctioned by usage. Nevertheless, it appears to me, my brethren, that such “a longing” is not fully satisfied even in the faithful in Baptism: but that haply, if they know where they are sojourning, and whither they have to remove from hence, their “longing” is kindled in even greater intensity.
Source: The Enarrations, or Expositions, on the Psalms (New Advent)