l
raise up unto thee a prophet from the midst of thee, of thy brethren,
like unto me; unto him ye shall hearken," Deut 18, 15. Again, "I will
put my law in their inward parts, in their heart will I write it; and
I will be their God, and they shall be my people," Jer 31, 33. And
again, "I will put enmity between thee and the woman," Gen 3, 15. Now,
these promises depend not in any way upon our works, but absolutely
and only upon the goodness and grace of God, because he was pleased to
make those promises and to do what he thus promised. Just in the same
way we have the promise of Baptism, of the Lord's Supper, and of the
Keys, etc., in which God sets before us his good will and his mercy
and his works.

224. Now, God gave no promise of the latter kind to Cain. He only said
to him, Whosoever shall slay thee shall be punished sevenfold. But
Adam had such a promise of grace made to him. And Cain, because he was
the first-born, ought to have received that promise as an inheritance
from his parents. That promise was the large and blessed promise of
eternal glory, because by it the seed was promised which should bruise
the serpent's head, and this without any work or merit of man. For
that promise had no condition attached to it, such as, If thou shalt
offer thy sacrifices, if thou shalt do good, etc.

225. If, therefore, you compare this promise of grace with the words
God spake to Cain, the latter are as a mere crust held out to a
beggar. For even Cain's life is not promised him absolutely. Nothing
more is said than a threat pronounced against those who should slay
him. God does not say positively, No man shall slay thee. He does not
say, I will so overrule all others that no one shall slay thee. Had
the words been thus spoken, Cain might have returned into the presence
of God and of his parents. But a command only is given to men that
they slay not Cain. If, therefore, the words spoken to Cain be at all
considered as a promise, it is that kind of promise which, as we have
before said, depends on the works and will of man. And yet, even such
promise is by no means to be despised, for these legal promises often
embrace most important things.

226. Thus, Augustine observes that God gave to the Romans their empire
on account of their noble virtues. And in the same manner we find,
even to this day, that the blessings of those nations which keep from
murder, adultery, theft, etc., are greater than those of other nations
in wh