St-Basil-the-Great‘The streams of the river make the city of God joyful’ (Psalm 45:5).

The briny seawaters, being exceedingly disturbed by the winds, roar and are troubled, but the streams of the river, proceeding noiselessly and flowing in silence to those worthy of receiving them, make the city of God joyful.

And now the just man drinks the living water and later will drink more plentifully, when he has been enrolled as a citizen in the city of God.

Now he drinks through a mirror and in an obscure manner (1 Cor. 13:12) because of his gradual perception of the divine objects of contemplation; but then he will welcome at once the flooded river, which is able to overwhelm all the city of God with joy.

Who could be the river of God except the Holy Spirit, who comes into those worthy because of the faith of the believers in Christ?

‘He who believes in me, as the Scripture says, “From within him there shall flow rivers”’ (John 7:38). And again, ‘If anyone drinks of the water which I give, it will become in him a fountain of water, springing up unto life everlasting’ (John 4:13-14).

This river, accordingly, makes all the city of God at once joyful, that is to say surely, the Church of those who hold to a heavenly manner of life. Or, every creature endowed with intelligence, from celestial powers even to human souls, must be understood as the city made joyful by the inflowing of the Holy Spirit.

Some give the definition that a city is an established community, administered according to law. And, the definition that has been handed down of the city is in harmony with the celestial city, Jerusalem above.

For, there it is a community of the first-born who have been enrolled in heaven (cf Heb. 12:23), and this is established because of the unchanging manner of life of the saints, and it is administered according to the heavenly law.

Therefore, it is not the privilege of human nature to learn the arrangement of that city and all its adornment. Those are the things ‘Eye hath not seen nor ear heard, nor has it entered into the heart of man, what things God has prepared for those who love him’ (1 Cor. 2:9),  but there are myriads of angels there, and an assembly of saints, and a Church of the first-born that are enrolled in heaven.

[…] Therefore, having raised the eyes of your soul, seek, in a manner worthy of things above, what pertains to the city of God…which the river of God makes joyful.

Basil the Great (330-379): Homily 18 (on Psalm 45[46]), 4,  from Saint Basil: Exegetic Homilies, translated by Agnes Clare Way, Catholic University of America Press (The Fathers of the Church, vol. 46), pp. 302-303.