The themes of the novel relate to the title through the notion of positive and empowered perspective. Celie and other characters in the novel grow and change with age, coming to recognize that individuals possess the power to choose how to express their own nature and how to actively be "themselves".
This thematic element is critical and central to the text. The title connects with this idea as the color purple becomes associated with the concept of God's expression and human joy.
In a conversation between Celie and Shug, the color purple is used as an example of one of the things people should enjoy as they look upon God's creation. Shug goes one step further and suggests that God is in all things. To enjoy the color purple, then, is to enjoy God.
The connection here between the color purple and God's expression extends directly to the notion of self-expression. When Celie learns to see the color purple as something to be enjoyed as a facet of God, she also learns to accept herself. Part of this change is related to her new and empowered perspective regarding her image of God.
Where she once saw God as a man, she now sees God as a part of everything. This de-centralization places her in a position of relative power compared to her former views. With self-acceptance and a new ability to love and accept herself, Celie learns to enjoy life, focusing on the positive and learning to forgive.