
Gregory the Great
Catena Aurea · Johannesevangelium 7
In the last day, that great day of the feast, Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink. He that believeth on me, as the Scripture hath said, out of his belly shall flow rivers of living water. (But this spake he of the Spirit, which they that believe on him should receive: for the Holy Ghost was not yet given; because that Jesus was not yet glorified.)
(super Ezech. Hom. x.) When sacred preaching floweth from the soul of the faithful, rivers of living water, as it were, run down from the bellies of believers. For what are the entrails of the belly but the inner part of the mind; i. e. a right intention, a holy desire, humility towards God, mercy toward man.