What was the ceremony in chapter 10 held for? What are the egwugwu?

Umuofia has a great clan gathering. Nine men in the cult of the egwugwu impersonate the nine founders of the villages of Umuofia. During the ceremony, the men are considered to be the spirits of the clan. The transformation is spiritual and complete, in the same way that Catholics believe that the bread and wine literally become the body and blood of Christ.

The ceremony is for the administration of justice. Families with disputes come forward to have their cases tried publicly. The first case involves a woman who has left her husband. He wants her to return, along with her two children. The woman's family claims that her husband was abusive. Evil Forest, the egwugwu who listens to the case, decides that the husband must bear gifts to his in-laws and beg his wife's forgiveness. She will return, but he should not beat her again.