Letter 80 is a rich storehouse of all the themes of the novel. The three most significant themes discussed are male and female relationships, African and black American relationships, and personal independence.
Concerning the second of these themes, you should be aware that Samuel and Nettie (now that Corrine is dead) are good missionaries, but they have no sense of place; they don't belong. They belong neither to the world of the European power structure nor to the traditional world of the black West African. They belong only to God and to one another. In the world of growing avarice and exploitation that is encroaching into the jungle, they are powerless. Samuel is disappointed that the Olinka never recognized them as blood brother and sister. In fact, the Olinka reject Samuel and Nettie, suspicious of their rejection of America's "progress" — motorcars, for example.
Had Samuel and Nettie not have gotten married, they both may have ended up feeling completely unappreciated. Samuel's character has the distinction of being the only accepting, loving, and giving husband in the entire novel.
The mention of "DuBoyce" in this letter is important. Nettie is actually discussing the great black American sociologist, philosopher, and civil rights leader, W. E. B. Du Bois, who was born in 1868 and died in 1963 in Ghana, West Africa. As a noted scholar, he tried to create an appreciation of black Americans, and he was instrumental in founding the National Association for the Advancement of Colored People (NAACP). He and Booker T. Washington, the founder of Tuskegee Institute in Tuskegee, Alabama, had a heated debate over the method by which blacks should advance. Washington stressed a practical economic freedom that would in time lead to a political and cultural freedom. Washington wanted blacks to get jobs as postal workers, carpenters, and repairmen. On the other hand, Du Bois wanted blacks to aspire to become professionals. His Harvard education made him fiercely defend the position that knowledge was the most important thing a man could acquire.
Walker presents Du Bois accurately in The Color Purple because he certainly would have been appalled at Aunt Theodosia's ignorance. He was a very austere, serious, and self-righteous man.
Doris Baines is a clever woman who has made herself happy in Africa. Writing saved her life. It is interesting that she chooses to call Harold her "grandson" for he is no blood relation to her. Since he is the offspring of one of her "wives," then he should be her "son." But Doris Baines thinks of her two wives as her daughters. She is delighted with the fact that she was a mystery to both the natives and her readers. She uses a male pseudonym and has two "wives," it is true, but she is no freak; she is a lively and kind woman.
Turning to Adam's infatuation with Tashi, we should recall Harpo's initial infatuation with Sofia. Here, Nettie is acting very much in the same capacity that Celie once did with Harpo long ago. Like Harpo, Adam believes himself to be deeply in love with Tashi, who is just as independent as Sofia was.
And similarly, just as Sofia was beaten in prison, Tashi is beaten during her female rite of passage; afterward, Nettie describes Tashi as looking "listless, dull-eyed and tired." When we compare Nettie's description of Tashi with Celie's description of Sofia in Letter 37, it is difficult to tell which woman was more mutilated.
Nettie closes Letter 81 with a sentence that magnifies the radiance of her sisterhood with Celie: "But all things look brighter because I have a loving soul to share them with."