He that believes on me, as the scripture has said, out of his heart shall flow rivers of living water.
All Commentaries on John 7:38 Go To John 7
Cyril of Alexandria
AD 444
He shews that vast and ageless is the reward of faith, and says that he who does not disbelieve shall revel in richest graces from God. For he shall be so replete with the gifts through the Spirit, as not only to fatten his own mind, but even to be able to overflow into others' hearts, like the river stream gushing forth the God-given good upon his neighbour too. This very thing used He to enjoin the holy Apostles, saying, Freely ye received, freely give. And the wise and holy Paul too himself longing to be effectual unto this writes, For I long to see you that I may impart some spiritual gift. And one may see this most exceeding well in both the holy Evangelists and in the Evangelic teachers of the church, who on those who go to Christ through faith pouring forth most plenteous word of inspired teaching, spiritually delight them, no more suffering them to thirst after the knowledge of the truth, with their wise soundings all but crying aloud into the heart of those who are being instructed. Wherefore the Psalmist rejoicing in spirit called out concerning them, The rivers lifted up, o Lord, the rivers lifted up their voices. Great and mighty sounded forth the word of the Saints, and into all the earth went forth their voice, as it is written, and unto the ends of the world their words. Such rivers did God, the God and Lord of all, promise to set forth to us, saying by the Prophet Isaiah, The beasts of the field shall honour Me, the dragons and the daughters of the owl, because I have given water in the wilderness and rivers in the thirsty ground to give drink to My chosen generation, My people whom I formed for Myself to shew forth My praises. Very evident then it is that the Saviour says that out of the belly of him that believeth shall come forth the grace that through the spirit giveth instruction and eloquence, whereof Paul too maketh mention saying, To one is given by the Spirit the word of wisdom.
It is good to know besides that the Saviour applied to His own words this saying, not exactly as it had been before put out by the Divine Scripture, but rather interpreting it according to its meaning. For we find of every one who honoureth and loveth God that he shall be like a watered garden, and like a spring whose water fails not. And what He says a little before to the woman of Samaria, this now too He clearly declares. For there He says, Whosoever drinketh of this water shall thirst again, but whosoever drinketh of the water that I shall give him shall never thirst, but the water that I shall give him shall be to him a well of water springing up into everlasting life: and here again carrying up the aim of His discourse to the same meaning, He says, Out of his belly shall flow rivers of living water.
