In his preface to Homecoming (1972), a volume of criticism, Ngugi has stated his frame of reference for writing literature. He sees a strong relationship between creative literature and the social, economic, and political forces in African society. It is therefore no surprise that Petals of Blood is a strong indictment of certain aspects of political and social life in modern Kenya. Freedom has not brought the kind of better life for which people hoped and sacrificed. Kenyans have merely exchanged white rulers for black rulers; corruption has become a cancerous growth in the nation’s life. These are the major themes of Petals of Blood.

The imagery of the title suggests that the flower of freedom is stained with blood. The fire set by Munira is the novel’s central action. This futile, destructive act of violence is an expression of the powerlessness of the common man, whose hopes have been betrayed by his own people. In showing how the principal characters, who have once shared a common outlook, end at cross-purposes, Ngugi implicitly calls for a commitment to collective action.

Alienation of the Land
Petals of Blood is an overtly political novel, and the author's intention is to present readers with a portrait of the economic, social, and other ills of post-independence Kenya. As he makes clear in his writings, Ngugi does not think that his role as a writer is to change society, because only people can change society. However, as he says in a 1979 interview in African Report, he thinks writers can point out where things are wrong and also that "fiction should embody the aspirations and hopes of the majority—of the peasants and workers.’’ Clearly the main concern in Petals of Blood is to draw attention to the plight to the dispossessed peoples of Ilmorog, and by extension, of Kenya. The novel shows that after decades of colonial rule, many of the poorer segments of Kenyan society have been alienated from the land, the source of life for centuries. Even after independence, this separation continues. Karega's mother, Miriamu, is forced to work as a laborer on Munira's father's land. The villagers are helpless in the face of a drought that threatens their life. The landscape of Ilmorog changes forever when the Trans-Africa Highway is built, dividing the village into two. With the transformation of Ilmorog to an industrial center, peasants are forced to pawn their land to obtain bank loans, which they cannot pay, and their ancestral homelands are seized by financiers. The land of the people becomes just another commodity in the hands of economic rulers as Ilmorog is transformed
from a bucolic rural village to a polluted industrial development.

Critique of Capitalism
Related to the theme of the people's alienation from their land is Ngugi's critique of capitalism. Capitalism is an economic system in which the means of producing wealth are privately owned. The novel denounces such a system that has created unequal classes of rich and poor by dramatizing its effects on the people of Ilmorog. The capitalists in the novel—including Kimeria, Chui, Mzigo—are seen as ruthless men who are unconcerned with the misery that their greed creates. They seek to suppress the workers' union and refuse to raise their wages. They drive expensive cars and want for nothing, while the villagers travel on foot to seek help in the face of famine. They take from the people of Ilmorog the recipe of their traditional alcoholic brew, Theng'eta, and make millions from it, forcing the townspeople to work in the factory under poor conditions. The novel also presents these entrepreneurs as working in collusion with Western corporations that continue to exploit the labor of the uneducated Kenyan masses. The revolutionary Karega, whom some critics have viewed as presenting Ngugi's opinions, sees that the only way to reconstruct a just society is to do away with the elite who amass riches at the expense of the people. He presents a vision of a socialist system in which the working classes, those who create the wealth, have access to the fruits of their labor by owning the means of production and so are no longer exploited and oppressed by corrupt businesspeople.

Village versus City
The contrast drawn between village and city in the novel serves to underscore the damaging effects of capitalism as well as to make clear the difference in values between traditional and modern Kenyan society. The village of Ilmorog had once been a thriving place set against a ridge that the novel's narrator says must have been "one of the greatest natural beauties in the world.'' Founded by a courageous herdsman, Ndemi, who began cultivation of the lands, it was once a place of peace, beauty, and dignity. After independence, Ilmorog has become a dusty and backward place, but the people still uphold their integrity. The community is close-knit and hold onto their values and beliefs, participating in communal rites and helping each other. Their values are seen in contrast to those of the urban elite, whose sole interest is money and power. The city is seen as a place of corruption and decay, with tall buildings and gardens as well as shantytowns and bars. Over the course of the novel Ilmorog is transformed from a rural village to an industrial center, and with it comes a disintegration of its values. Wanja, who has been forced to give up her successful business and turn to prostitution in order to avoid being exploited in other ways, says of the values of the city and the "New Kenya'': "You eat somebody or you are eaten. You sit on somebody or somebody sits on you.’’

The Struggle for Independence
The novel details the heroic struggles of the freedom fighters, many of whom gave up their lives to achieve independence, or Uhuru, for Kenya. The village elder Nyakinyua recounts her husband's exploits and his proud refusal to be humiliated by the British. Karega's brother, Nding' uri, gave up his life for the cause as a Mau Mau rebel. And Abdullah, who has lost his leg during the resistance, is a reminder of the sacrifices made by the common people in the struggle for freedom from colonial rule. Now that independence has been achieved, however, the people who fought so bravely for their country are not rewarded. Rather, they are dispossessed by the wealthy few who did not participate in the struggle at all. Those like Mzigo and Kimeria who stayed in school or were involved in business during the movement have reaped the rewards of independence. With their money they have appropriated the land of the peasants who bought the country's freedom, leaving them dispossessed and without a means of livelihood. These entrepreneurs are seen as continuing the practices of the British oppressors, as they force peasants to work at subsistence wages on land that was traditionally theirs.

Christianity
Although the critique of Christianity in the novel is not as overt as are its social and political indictments, it seems clear that Ngugi means to point out the hypocrisy that attends many forms of Christian religious practice. There are no sympathetic portrayals of Christians in the novel. Ezekiel Waweru and the Reverend Jerrod Brown are seen as using Christianity to further their own material interests. Both have adopted the Christianity of the colonial masters and perpetuate the inequality of their system of values. When the villagers first encounter Reverend Jerrod Brown they assume he must be a white European because of his name. He offers them no help with the sick child, Joseph, nor does he give them food, and tells them they need only eat "the food of the spirit, the bread and fish of Jesus.’’ Waweru has adopted the Christianity of the missionaries because it is more profitable for him to do so, but shows no Christian compassion to his son, daughter, or the laborers on his land. The Christian Lillian is also presented as a crazed fanatic who ignores the problems of this world by emphasizing life in the next, a strategy which she eventually gets Munira also to adopt.

Oppression
One of the persistent themes of Petals of Blood is oppression—social, economic, political, racial, and sexual. By oppressing them, or controlling the direction of people's lives, colonial and neocolonial rulers prevent ordinary Kenyans from reaching their full potential. The treatment of social, economic, and political oppression is tied in with the novel's critique of capitalism and the alienation of the people from their traditional work. Racial oppression is explored in attitudes of Europeans to Kenyans during colonial rule, particularly those of people like Fraudsham who view Africans as having to conform to a standard of behavior set by the British. The concern with sexual oppression becomes clear in the figure of Wanja, a woman of great energy, intelligence, and sensitivity whose only recourse in the face of economic failure and exploitation is to turn to prostitution and to serve the interests of men. Throughout the novel, peasants and workers are prohibited from prospering because of the oppressive external forces of colonialism and capitalism. In the figures of Joseph and Karega it is seen that it is possible for the Kenyan peasantry to flourish if, like flowers, they are exposed to nourishment and light and not prevented from shaping their own destiny.

Education
There is a great deal of discussion and action in the novel surrounding education. Four important characters—Munira, Chui, Karega, and Mzigo— are teachers. Munira, Chui, and Karega attended Siriana High School and were expelled for their revolutionary activities, which did much to determine how they would view their futures. Joseph earns a scholarship to Siriana also, and seems to exhibit the same idealism as that shown by the others. The future of the country seems to lie in what he will make of his experience there. Cambridge Fraudsham, the English headmaster of Siriana, represents the arrogance of the colonial school system, with its irrelevant curriculum that is forced upon Africans and its systematic degradation of its students because of their race. Like Ngugi, Karega and the other students who strike want the Kenyan educational system to reflect the contributions and experiences of Africans and not simply those of white Europeans. The hope for reform at Siriana is dashed when Chui, "a black replica of Fraudsham'' takes over and forces students to conform to the same principles as those of the British. With this theme Ngugi again emphasizes that the new leaders in Kenya follow the same path as the oppressors they have just overthrown. Education also serves to contrast the characters of Munira and Karega. Munira has come to Ilmorog to be a teacher but he is not concerned with the welfare of his students as much as to be revered himself. He thinks the pupils should be given ‘‘simple facts’’ so they can pass their exams. Karega sees his students as thinking beings and he takes it as his duty to help them shape their future and their lives. As a union organizer he continues to teach workers and others about the truth—of the destructive powers of capitalism and the possibility for a better socialist society.