Colonialism/Imperialism
The River Between is an allegory of the colonization of Kenya when the British introduced Christianity and exploited the country. Joshua represents the converted African who does everything in his power to support the colonialists, represented by a man called Livingston (possibly referring to David Livingston, the pioneer missionary). The British secure their power by building government posts and collecting taxes, which at first does not concern the people because they do not know what taxes are. Only later do they realize that they are exploited. Therefore, Waiyaki tries to lead his people to independence through (Western) education, after his father tells him, "Learn all the wisdom and all the secrets of the white man. But do not follow his vices." However, in the end, he realizes that education alone is not enough to improve the lives of the people. Instead, it is necessary that the community gains self-respect through political action uniting the different tribes.
Individual vs. Community
The two characters that try to follow their own agenda without first consulting with the elders and their community meet with an unfavorable end. Waiyaki keeps building more schools in an attempt to provide education to the people, but even though he has good intentions, he underestimates the power of the council of the elders, who consider adhering to ancient traditions more important than taking over parts of the white man's culture. In the end, he is punished by the council and the people, which indicates that all his efforts were in vain. Similarly, Muthoni goes against the will of her father and Christian community when she decides to follow the traditions and get circumcised to become part of the tribe. Muthoni dies because of this procedure, which also indicates that reconciliation is impossible.
Self-Knowledge (or lack thereof)
Waiyaki's main flaw seems to be that he is not entirely self-aware. He knows he is a vital member of the community and most of the time sees himself as the savior from Chege's prophecy, but he is incapable of acknowledging that his vision for the tribe may not be what the tribe actually needs. He also cannot really see how crucial his failure to talk about unity was, and how he is being selfish by putting it off. He ignores aspects of what his elevated role in the society might mean for himself and others.
Tradition
Tradition is exceedingly significant to a society, especially in terms of their founding history, rites, rituals, etc. The Kikuyu have long held their own beliefs on these subjects, and the white man's influence is seen as deleterious to those beliefs. Ngugi suggests that not all new ideas are bad—Waiyaki and Muthoni and Nyambura articulate the need for a fusion between Christianity and tribal tradition—and that traditions can be problematic. He is aware, though, that traditions are excessively difficult to change or eradicate, and that the white man and his African supporters cannot expect to order the Kikuyu to get rid of something overnight. Rather, patience and understanding are necessary.
Unity and Division
Ngugi evinces complicated views on human nature, suggesting that both unity and division can be sustaining and dangerous in various circumstances. The two ridges are unified by the river but at the same time divided by it; there is neutral ground but it is nearly impossible to occupy. Division is present in the novel through the white man and his religion/education/influence; as we watch, various Kikuyu come down on either side of these encroachments. Division is natural because a population cannot be perfectly homogeneous; however, these divisions can become dangerous when they are accompanied by violence, ignorance, and intolerance. There is a need for unity on the basis of something deeper to preclude the complete fraying of a society. Thus, by the end of the novel unity is needed to patch the two ridges together in order to maintain autonomy over a way of life—but Ngugi indicates that this is a difficult thing to achieve.
The Land
The land is of paramount importance in the text. Ngugi begins the novel with an image of its ancient presence, its sustaining nature, and its centrality to rite and ritual (as seen, for example, in the way that the circumcision and initiation ceremonies are tied to the river). The land is tied to culture, and when the Kikuyu feel like their land is under siege by the white man, it is so much more than that. That the white man builds on their land, taxes their land, and eventually will take their land is what so horrifies the Kiama; even though Waiyaki is the central protagonist, the reader feels sympathetic to the Kiama's goal of routing the outsiders.
Courage
The characters in The River Between exhibit courage in a variety of ways. Sometimes this courage is standing up to family or to the community, and sometimes it is being honest with oneself. Muthoni has convictions that necessitate her standing up to her family, and Nyambura stands up to her family and her community for love. Similarly, Waiyaki demonstrates courage as he pursues his goal of education, as he seeks unity between the ridges, and as he defends his love for Nyambura. Having courage doesn't guarantee a positive outcome, but it can foster a sense of wholeness and peace in a person.
