Ambrose of Milan : "There is grain in Egypt"; that is, where the famine is greater, the abundance is greater. There is much grain in Egypt. Surely, and God the Father says, "Out of Egypt I called my son!" Such is the fecundity of that grain, for there could not have been a harvest unless the Egyptians had sown the grain earlier. There is then grain that no one earlier believed to exist. The patriarchs engaged in negotiations in regard to this grain. And they indeed brought money, but the good Joseph gave them the grain and gave them back the money. For Christ is not bought with money but with grace. Your payment is faith, and with it are bought God's mysteries. Moreover, this grain is carried by the ass, which before was unclean according to the law but now is clean in grace. — On Joseph the Patriarch