The Day of Atonement — Leviticus 16

Lev 16:14-22 prescribes the Day of Atonement: blood sprinkled on the mercy seat, and a second goat sent into the wilderness bearing the people's iniquities. Propitiation and removal of sin are enacted in one rite.

Thomas Aquinas — Summa Theologiae, and John Owen — The Death of Death in the Death of Christ. The mercy seat (kapporet) is the meeting place of holiness and mercy.

Hebrews makes this the controlling type for Christ's priesthood in Heb 9:11-14, and Paul calls Christ the hilasterion — the mercy seat — in Rom 3:25. The scapegoat's burden anticipates the Servant of Isa 53:6.