We are going to sing the "Passer invenit" this Sunday, which happens to be one of my favourite communion antiphons. Here's a commentary from Dom Johner's Chants of the Vatican Graduale regarding this piece:
In the three phrases of this piece there is mention of a threefold kingdom. The first speaks of the realm of Nature, of the birds and the nests in which they harbor their young. We are struck by the numerous podatus forms, which may, in the composer's mind, indicate the fluttering of birds. That which is expressed pictorially in the first phrase, in the second becomes a reality, even though mysteriously, in the realm of mystery, in the kingdom of grace. From the altar and its Mystery flow the strength by which the Lord of hosts—the melody stresses this word—becomes our King, our God. There the soul has found her earthly home; there she is harbored safely and securely; thence she draws a marvelous fecundity. Such was the yearning of the catechumens: to be privileged to draw nigh to the altar. And the penitents, who had to remain outside the church during Lent, how will they envy the good fortune of those who come out with the Saviour in their heart! The third phrase refers to the kingdom of glory, to the house of God, where we shall sing praises for a blessed eternity. How luminous the melody here is! There we shall sing Alleluia in unending Paschal joy. There we shall forever sing our joyous thanksgiving for the boon God has bestowed upon us; for now evellet of the Introit has become full reality. There we shall sing an everlasting Redemisti nos-—Thou hast redeemed us with Thy blood; our soul has escaped like a bird from the snares of the fowler: the snare is torn and we are freed. For this happiness the Mysteries of the altar are to prepare us. Holy Communion gives us the strength requisite to attain eternal glory. Our praying and singing in the house of God is a preparation for that more sublime song of eternity. May God's merciful love one day bring us all together in that celestial choir!
Lovely, isn't it?