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The Feast of the New Yam occurs at the beginning of Chapter Five of this great novel dealing with the clash of two radically different civilisations. We are told that this feast is an occasion to give thanks to Ani, the goddess of fertility and of the earth, the most important deity for the tribe. Note the following description:
The Feast of the New Yam was held every year before the harvest began, to honour the earth goddess and the ancestral spirits of the clan. New yams could not be eaten until some had first been offered to these powers. Men and women, young and old, looked forward to the New Yam Festival because it began the season of plenty - the new year.
Therefore, because of this, old yams are disposed off and the new year can only begin with fresh yams. All cooking utensils are likewise cleaned. So much yam foo-foo and vegetable soup is made that there was always food left over no matter how many guests are invited. It was expected that strong men would invite many guests. However, it is interesting that Okonkwo does not like this festival and the joy it brings, as he struggles with inactivity and not working. This suggests a lot about the nature of his character.