The Two Goats on Yom Kippur:
Read Rabbi Sacks on the שעיר לעזאזל - The Scapegoat.
" It was a protest against human sacrifice, widespread in the ancient world and still, in quite different forms, alive today in the form of conspiracy theories, terror, suicide bombings and ethnic conflict. Two features of the high priest's ritual were crucial:  that the sacrifice was an animal, not a person, and  that it was not an occasion for denying responsibility by blaming the victim, but to the contrary an acceptance of responsibility in the context of repentance and atonement. "
BTW excellent pictures of the Avodat Yom Hakippurim can be found here.