What is the theme in The Purple Flower by Marita Bonner?

Slavery is the main theme of the story. Although the Us's in tins play are not slaves, their socioeconomic situation represents that of the legacy of slavery in the lives of African Americans. An introductory explanation of the play states that the Us's "tilled the valley, they cultivated It and made It as beautiful as it is. They built roads and houses even for the White Devils." This description represents the fact that the prosperity of the United States was built in part by the labor of African American slaves and, after emancipation, by low-wage labor.