Intro
Things Fall Apart is generally seen as Achebe's way of taking back Africa from Joseph Conrad and Heart of Darkness. More than that, it's Achebe's way of talking back to Conrad about Africa.
The novel focuses on the Igbo people in the years leading up to the arrival of the first Christian missionaries—it follows Okonkwo, a respected member of the tribe, as he builds up his reputation; knocks it down again with some accidental murders; loves, raises, and kills an adoptive son; and is exiled for killing a different boy. Basically, we get to see the ins and outs of pre-colonized Africa and get a hint of what's to come when the missionaries show up.
So here's Achebe's quandary: how does he remain a hardcore critic of a colonial regime that imposes its language on a native population when he himself writes (and writes so well) in English—the tongue of the colonizer?
These days, most scholars read Achebe's quandary as what it is: a problem that greets most postcolonial writers who have no real choice but to write in the dominant (or "'hegemonic"') language since that's what they were taught.
The real question becomes: does the writer (in this case, Achebe) do anything to question, "'problematize,"' or revolutionize that dominant language so that we—as readers—are aware of the problems that come with writing and speaking the "'master's language"'? And, for the most part, postcolonial scholars do get that Achebe tries something different with language in his novel.
The way he incorporates the language of the Igbo people into the story itself is often seen as his attempt to put a "'native"' language other than English front and center. That way we get to see what we are missing as English readers.
Quote
Okonkwo had just blown out the palm-oil lamp and stretched himself on his bamboo bed when he heard the ogene of the town crier piercing the still night air. Gome, gome, gome, gome, boomed the hollow metal. Then the crier gave his message, and at the end of it beat his instrument again. Again this was the message. Every man of Umuofia was asked to gather at the market place tomorrow morning. Okonkwo wondered what was amiss, for he knew certainly that something was amiss. He had discerned a clear overtone of tragedy in the crier's voice, and even now he could still hear it as it grew dimmer and dimmer in the distance.
Analysis
Here's a perfect example of how Achebe inserts the language of the Igbo people into the novel. "'Ogene,"' "'gome"': these are words that—we're guessing—can't be translated precisely into English. And heck—even if they could, isn't it so much cooler to read the words in their original language? That way, at least you can get a (faint) sense of what the Igbo language sounds like and how the Igbo hear their own language.
Take "'gome"' for example. We're guessing that this sound comes from the "'ogene,"' which seems to be a "'hollow metal"' instrument of the town crier. Kind of like a gong. Which sounds kind of like "'gome."' But for real: does the "'hollow metal"' make a sound that can actually be called "'gome"'? All we can say is maybe.
And that's the whole point! Even the sound of an instrument is heard differently based on the language you're used to hearing things in. Is the spelling and translation subjective? Sure! Just like the way we interpret a dog's bark to be "'ruff"' or "'bow-wow"' in English, whereas the way a French person interprets and spells a dog's bark may be way different (wouaff-wouaff, to be precise—and other languages get even weirder).
So how we name sounds, things, people, places…all that is given to change over time and place. That's how we get different languages and cultures. Achebe shows us how invented language fundamentally is, so that—just maybe—we can view the English language as an invented thing too. Something, in other words, that is impermanent and, therefore, not innately superior to any other language.
That last point is an important one, and Achebe shows us why (warning: not total spoiler alert, but foreshadowing!). Okonkwo feels that something's "'amiss"' and hears a tragic tone in the crier's voice, a sound that "'gr[ows] dimmer and dimmer in the distance."' That ever-fading sound is a lot like what happens to the Igbo language in the book and—we'll guess—possibly in real life as well.
That dimming, pretty much, is what happens to many indigenous languages when a colonial power comes in and forces a new language on the people of another land. The indigenous language starts to fade away. People start to forget it and, pretty soon, you have whole generations who no longer speak the Igbo tongue (for example) because they're speaking English or some other language.
So, let's say one day someone decides they really want to write a novel (like, ahem, Things Fall Apart). That aspiring author ends up writing their story in English and not in Igbo. That means the writer is forced to translate his or her culture in another language; perhaps the writer even lives his or her own culture in translation.
And you know what they say about translations: something is always lost. But that doesn't mean something else—a new view, a hybrid one, a postcolonialist one—can't be gained at the same time.