The first reading tells how the people entered into the Old Covenant with God. A covenant, as in our marriages, is a contract by which the parties give themselves to each other so that they can become one. With our marriages the priest asks, “Have you come here freely without reservations to give yourselves to each other in marriage?” The only way the Israelites could become one with God was for them to keep his commandments.
Moses assembled all the people before Mount Sinai, and he had the young men do two things. First in front of the mountain he had them build an altar to represent God. Secondly, he had them kill some bulls, bringing in the blood of the bulls in big brass bowls.
He they read off the Ten Commandments one at a time, asking them if they would obey each. At the same time the young men circulated through the crowd sprinkling them with blood, and pouring the last of it from each bowl on God’s altar.
The Israelites believed that blood was life itself, and that the life force in the drops was uniting them in one life with each other and with God.