Leviticus 16:14 NKJV
He shall take some of the blood of the bull and sprinkle it with his finger on the mercy seat on the east side; and before the mercy seat he shall sprinkle some of the blood with his finger seven times.
God gave Moses instructions to give the high priest, Aaron about approaching the mercy seat. Aaron had to appear before the mercy seat to obtain pardon from sin for the nation. A part of what he had to do was sprinkle blood on the east side of the mercy seat seven times. I believe that this symbolized the significance of the role blood played in the dispensing of mercy. The blood of bulls and goats in the Old testament represented the blood of Jesus that was to be shed for the sins of the mankind. The Old Testament blood sacrifices were a temporary fix until Jesus came. That is why the sacrifices had to occur over and over again. Once Jesus, the Lamb of God came and offered Himself, He became the final sacrifice. His blood was able to accomplish once what the blood of bulls and other animals could not accomplish after thousands of sacrifices had been made. That maybe one reason a songwriter said , "There is power, power, wonder-working power in the blood of the Lamb." Hebrews 9:22 tells us that without the shedding of blood there is no remission or release from guilt and punishment that result from sin. So the blood allows God's mercy to be extended to us. Thank God for His mercy and the blood of Jesus that makes that mercy available to us.