5 “My soul is thirsty for the living God”. What I am saying, that “as the hart pants after the water-brooks, so longs my soul after You, O God,” means this, “My soul is thirsty for the living God.” For what is it thirsty? “When shall I come and appear before God?” This it is for which I am thirsty, to “come and to appear before Him.” I am thirsty in my pilgrimage, in my running; I shall be filled on my arrival. But “When shall I come?” And this, which is soon in the sight of God, is late to our “longing.” “When shall I come and appear before God?” This too proceeds from that “longing,” of which in another place comes that cry, “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.” Wherefore so? “That I may behold” (he says) “the beauty of the Lord.” “When shall I come and appear before the Lord?”...
Source: The Enarrations, or Expositions, on the Psalms (New Advent)