Water is the "matter" of the sacrament, because it stands for the whole of matter, which is, in baptism, the sign and presence of the world itself. In the biblical "mythological" world view - which incidentally is more meaningful and philosophically consistent than the one offered by some "demythologizers" - water is the "prima materia", the basic element of the world. It is the natural symbol of life, for there is no life without water, but it is also the symbol of destruction and death, and finally, it is the symbol of purification, for there is no cleanliness without it. In the Book of Genesis creation of life is presented as the liberation of the dry land from the water - as a victory of the Spirit of God over the waters - the chaos of nonexistence. In a way, then, creation is a transformation of water into life.
The sacrament of forgiveness if baptism, not because it operates a juridical removal of guilt, but because it is baptism into Jesus Christ, who is the Forgiveness. The sin of all sins - the truly "original sin" - is not a transgression of rules, but, first of all, the deviation of man's love and his alienation from God. The man prefers something - the world, himself - to God, this is the only real sin, and it it all sins become natural, inevitable. This sin destroys the true life of man. It deviates life's course from its only meaning and direction. And in Christ this sin is forgiven, not in the sense that God now has "forgotten" it and pays no attention to it, but because in Christ man has returned to God, and has returned to God because he has loved Him and found in Him the only true object of love and life.
From For the Life of the World.