What is this ”water” in ”wells of salvation” that Isaiah speaks of here, and how is one to draw such water up?
The living water is a gift of the Holy Spirit. Cyril of Alexandria offers the following comments on this subject matter in Pope John Paul II’s Commentary/Meditation on Isaiah 12:1-6.
The salvation granted by God, that can make joy and trust flower even on the dark day of the trial, is portrayed by the classic image in the Bible of water: “You will draw water with joy at the fountain of salvation” (Is 12,3). It reminds us of the scene of the Samaritan woman, when Jesus offers her the possibility of having in herself a “spring of water that will well up to eternal life” (Jn 4,14).
Cyril of Alexandria commented in a marvelous way: “Jesus calls the life-giving gift of the Spirit living water, the only one through which humanity, even though it was completely abandoned, like the tree trunks on the mountains, and dry, and deprived of every kind of virtue by the deceit of the devil, is restored to the former beauty of its nature…. The Saviour calls the grace of the Holy Spirit water, and if one participates in him, he will have in himself the source of divine teachings, so that he will no longer need the advice of others, and will be able to exhort those who are thirsting for the Word of God. Such were the holy prophets and apostles of God and their successors in the ministry while they were alive on earth. Of them it is written: “You will draw water with joy at the fountain of salvation” (Commento al Vangelo di Giovanni [Comment on the Gospel of John], II, 4, Roma 1994, pp. 272,275).