Leo the Great

[The Lord] ascended into the retirement of a neighboring mountain and called his apostles to him there. From the height of that mystical seat he could instruct them in the loftier doctrines, signifying from the very nature of the place and act that it was he who had once honored Moses by speaking to him. He spoke with Moses then, indeed, with a more terrifying justice, but now with a holier mercy in order that what had been promised might be fulfilled when the prophet Jeremiah says, "Behold, the days are coming when I will complete a new covenant for the house of Israel and for the house of Judah. After those days, says the Lord, I will put my laws in their minds, and in their heart will I write them." He therefore who had spoken to Moses, spoke also to the apostles, and the swift hand of the Word wrote and deposited the secrets of the new covenant in the disciples' hearts. There were no thick clouds surrounding him as of old, nor were the people frightened off from approaching the mountain by frightful sounds and lightning. Rather, quietly and freely his discourse reached the ears of those who stood by. In this way the harshness of the law might give way before the gentleness of grace, and "the spirit of adoption" might dispel the terrors of bondage.