How is the Mother of the Spirits song of mourning a device of both symbolism and foreshadowing?

That night, the Mother of Spirits roams the villages, weeping for the death of her son. The spectacle is terrifying. Mr. Smith hears it, and for the first time feels fear. The egwugwu approach the church. They will not harm the people, but they could no longer allow the church to work its evil among the Igbo. They destroy the building. The symbolism and foreshadowing is cleear: the demise and eventual death of the Igbo culture as they know it.