1529 · Martin Luther, The Large Catechism 4
In the second place, since we know now what Baptism is, and how it is to be regarded, we must also learn why and for what purpose it is instituted; that is, what it profits, gives, and works. And this also we cannot discern better than from the words of Christ above quoted: He that believeth and is baptized shall be saved. Therefore state it most simply thus, that the power, work, profit, fruit, and end of Baptism is this, namely, to save. For no one is baptized in order that he may become a prince, but, as the words declare, that he be saved. But to be saved, we know, is nothing else than to be delivered from sin, death, and the devil, and to enter into the kingdom of Christ, and to live with Him forever. Here you see again how highly and precious we should esteem Baptism, because in it we obtain such an unspeakable treasure, which also indicates sufficiently that it cannot be ordinary mere water. For mere water could not do such a thing, but the Word does it, and (as said above) the fact that the name of God is comprehended therein. But where the name of God is, there must be also life and salvation, that it may indeed be called a divine, blessed, fruitful, and gracious water; for by the Word such power is imparted to Baptism that it is a laver of regeneration, as St. Paul also calls it, Titus 3:5.