Chapter Four is the section of this brilliant novel that you will want to re-read. This chapter tells us that the Week of Peace is a festival that is celebrated each year and that it comes between the time of harvest and planting. This Week of Peace is designed to ensure a bountiful harvest from the gods before the seeds are planted, and is a way of ensuring that the tribe gains the blessing of the earth goddess. Note what is said to Okonkwo when he breaks this tradition:

You know as well as I do that our forefathers ordained that before we plant any crops in the earth we should observe a week in which a man does not say a harsh word to his neighbour. We live in peace with our fellows to honour our great goddess of the earth without whose blessing our crops will not grow.

The Week of Peace therefore functions as yet another example of how strongly this tribe lives under the law of taboo and tradition, and how they will avoid doing anything that will anger the gods and threaten their survival. However, the second way it functions is to give us a clear indication of the kind of character Okonkwo is. He becomes so angry that he beats his wife in spite of this taboo. Okonkwo therefore shows himself to be a character who becomes easily overwhelmed by his emotions, in particular his anger. It is this anger that leads him to act impulsively without thinking about the consequences of his actions. This of course foreshadows a point later on in the novel when he becomes similarly overwhelmed by his anger and acts rashly, with horrendous consequences.