Reflecting on Christ’s words to the Samaritan woman at the well, John Calvin (1509-1564) recognizes the importance of the living water the Lord gives to those he chooses. The grace symbolized in this water, says Calvin, comes not through a single infusion, but is poured out through a lifelong relationship, and while believers will continually thirst for its sustenance, it pours fourth in abundance from a well that never runs dry.

John 4:13-14

Jesus answered, “Everyone who drinks this water will be thirsty again,14 but whoever drinks the water I give them will never thirst. Indeed, the water I give them will become in them a spring of water welling up to eternal life.”

Commentary on John 4:13-14

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.

John 1-12, Reformation Commentary on Scripture NT vol. 4, 131.