St. John Chrysostom says the Old Testament was preparing us for the New, God providing prophecy not only in words but also by example. All God’s words and deeds were preparing the world for the greater thing God planned to do – the incarnation of the Word in which God reunited earth to heaven. Prophecy and promise were done so that people would not find the great work of God to be unbelievable. God’s actions were done so people would be ready when God made Himself visible in the incarnation.
“Now, since we are delivered from the controversies with the Jews, I shall demonstrate this to you from the New Covenant, so that you will see the agreement of the two covenants. Did you see the prophecy that was made with words? Learn the prophecy that was made with examples; although even this is not yet totally clear, I wonder, what is prophecy by example, and I wonder what is prophecy by word? Shortly, I will make this clear, too. The prophecy that is made by example is the practical prophecy, and the other prophecy is the theoretical prophecy. In other words, the most prudent He persuaded with words, and the most unconscious He informed by showing them examples.
Because, in other words, something big was going to happen: God was about to take upon Himself human flesh. Because the earth was going to become heaven and our nature was going to be elevated toward the nobility of the angels. Because the word surpassed the hope and expectation of the future goods that were to come. So he would not confuse the people with the new and paradoxical event of the Incarnation, those who then would have seen it all at once, and those who were going to hear it, for this reason, He iconically depicted it beforehand with examples and words, and, in this way, He accustomed our hearing and vision.”