This day was not set for the annual Day of Atonement, without which the world could not exist, and which will continue even in the future world when all other holy days will cease to be. The Day of Atonement, however, is not only a reminiscence of the day on which God was reconciled to Israel and forgave them their sins, but it is also the day on which Israel finally received the Torah. For after Moses has spent forty days in prayer, until God finally forgave Israel their sins, he began to reproach himself for having broken the tables of the law, saying" "Israel asked me to intercede for them before God, but who will, on account of my sin, intercede before God for my sake?"
Then God said to him: "Grieve not for the loss of the first two tables, which contained only the Ten Commandments. The second tables that I am now ready to give thee, shall contain Halakot, Midrash, and Haggadot."