It is said that Christ is a river of water, because there is such a fulness in him, so plentiful a provision for the satisfaction of the needy and longing soul. When one is extremely thirsty, though it is not a small draught of water will satisfy him, yet when he comes to a river, he finds a fulness, there he may drink full draughts. Christ is like a river, in that he has a sufficiency not only for one thirsty soul, but by supplying him the fountain is not lessened; there is not the less afforded to those who come afterwards. A thirsty man does not sensibly lessen a river by quenching his thirst.

Christ is like a river in another respect. A river is continually flowing, there are fresh supplies of water coming from the fountain-head continually, so that a man may live by it, and be supplied with water all his life. So Christ is an ever-flowing fountain; he is continually supplying his people, and the fountain is not spent. They who live upon Christ, may have fresh supplies from him to all eternity; they may have an increase of blessedness that is new, and new still, and which never will come to an end.

—Jonathan Edwards
The Works of Jonathan Edwards, 2:932.