This is seomthing I reda in another forum. When a person wanted to be forgiven, the levetical priest would offer a sacrife for that Sin. When he did this the sinner would place his hand on the priest. The preist was the connection between the person and the sacrife. In other word the preist would connect the sinner with the sacrifice for atonement of the sin.
Similarly the preist becomes the vessel that connects us to the sacrife of Jesus, then absolution is given. Then of course we have to do our penance and put on the new.