From the beginning God formed man in view of his gifts.
He chose the Patriarchs in order to save them. He began to prepare a people, teaching it, obstinate as it was, to follow him.
He provided Prophets, to make men accustomed to having God’s Spirit within them and to having communion with God.
God indeed needed no one’s company, but he shared his company with those who needed him.
For those who pleased him he set down, like an architect, his plan of salvation. In his own person he gave guidance to his people in Egypt, though they did not see him.
To those in the desert, who were restless, he gave an appropriate Law. To those who entered the good land he gave a fitting inheritance.
For those who returned to the Father he killed the fatted calf, and put on them the best robe in these many ways he blended the human race to a harmony of salvation.
For this reason John said in the Apocalypse, His voice was like the sound of many waters. The Spirit of God is indeed like many waters, because the Father is both rich and great.
And the Word passing through all those men, without grudging gave help to all who were obedient by drawing up in writing a Law adapted and applicable to every class among them.
By this Law he prescribed how they were to make the Tabernacle, build the Temple, choose Levites, offer sacrifices and oblations, carry out rites of purification, and fulfil all the rest of their service. He himself has no need of these things.
[…] The people were quick to turn back to idols, but God instructed them. Many times he freed them, urging them to persevere in his service.
He called them to things of supreme importance by means of things of less importance, that is, he called them by shadows to those things which are real; he called them by temporal things to eternal things, by the carnal to the spiritual, by the earthly to the heavenly.
God told Moses, See that you make them all after the pattern which you have seen on the mountain.
For forty days Moses was learning to remember God’s words, the heavenly patterns, the spiritual images, the foreshadowing of things to come.
[…] Paul, again, listed the things which were in the Law, and concluded, All these things happened to them but they were written down as a warning to us upon whom the end of the ages has come.
By means of shadows they began to learn the fear of God and perseverance in his service. So the Law was both instruction for them and the foretelling of things to come.
Irenaeus of Lyons (2nd century AD – c. 202): Adversus Haereses 4.14.2-3; 15, 1; from the Monastic Office of Vigils, Thursday of the Fourth Week of Lent, Year 2.