John 4:13

13. Every one that drinketh of this water. Though Christ perceives that he is doing little good, and even that his instruction is treated with mockery, he proceeds to explain more clearly what he had said. He distinguishes between the use of the two kinds of water; that the one serves the body, and only for a time, while the power of the other gives perpetual vigor to the soul. For, as the body is liable to decay, so the aids by which it is supported must be frail and transitory. That which quickens the soul cannot but be eternal. Again, the words of Christ are not at variance with the fact, that believers, to the very end of life, burn with desire of more abundant grace. For he does not say that, from the very first day, we drink so as to be fully satisfied, but only means that the Holy Spirit is a continually flowing fountain; and that, therefore, there is no danger that they who have been renewed by spiritual grace shall be dried up. And, therefore, although we thirst throughout our whole life, yet it is certain that we have not received the Holy Spirit for a single day, or for any short period, but as a perennial fountain, which will never fail us. Thus believers thirst, and keenly thirst, throughout their whole life; and yet they have abundance of quickening moisture; for however small may have been the measure of grace which they have received, it gives them perpetual vigor, so that they are never entirely dry. When, therefore, he says that they shall be satisfied, he contrasts not with Desire but only with Drought

Shall be a fountain of water springing up into eternal life. These words express still more clearly the preceding statement; for they denote a continual watering, which maintains in them a heavenly eternity during this mortal and perishing life. The grace of Christ, therefore, does not flow to us for a short time, but overflows into a blessed immortality; for it does not cease to flow until the incorruptible life which it commences be brought to perfection.,