The very first of the psalms contrasts the good man with the wicked one, and says that the good man is like a tree planted by streams of water. In an arid part of the world like Israel in which the psalms were composed, it is very evident that water is crucial for life, growth, prosperity -- both for plants, animals, and human beings. Thus time and again, there are biblical references to water and its life-giving effects. While thinking of this, you might find it very helpful to read the fourth chapter of the gospel of St. John, in which Jesus speaks to the Samaritan woman at the well. He speaks of giving her "living water." And goes on to say, "Anyone who drinks the water that I shall give will never be thirsty again."