Coherence: Make Your Sentences Add Up to Something

Think of your text like a jigsaw puzzle.

One quality of puzzles is about the pieces fitting together smoothly. Each piece connects to the next. And when readers process sentences that link together in this way—with the end of one piece slotting in to the start of the next one—they experience flow, a powerful writing tool.

But there's a second quality of puzzles shared by clear writing: all those pieces need to create a unified picture.

A puzzle where the pieces connect perfectly but amount to no recognizable image is just as disappointing as one where the pieces don't fit.

That second quality is coherence—the sense that a passage is about something, that it's going somewhere, that the sentences add up to a whole.

What It Is

Coherence is the technical name for what happens when the reader experiences your passage as a unified whole.

It's different from flow (aka cohesion, which connects individual sentences) because it operates at a higher level of resolution. A passage can flow smoothly from sentence to sentence and still feel incoherent if the sentences don't share a common focus.

Here's a passage that flows perfectly but is completely incoherent:

Each sentence connects smoothly to the next.

• Coffee roasting at the end of Sentence 1 → The aroma of roasting beans at the start of Sentence 2;
• Gleaming espresso machines at the end of Sentence 2 → The machines at the start of Sentence 3;
• My dad's old typewriter at the end of Sentence 3 → His typewriter at the start of Sentence 4;
• Jammed on me at the end of Sentence 4 → That's why I at the start of Sentence 5
• Avoiding typewriters at the end of Sentence 5 → Prefer to write on legal pads at the start of Sentence 6 → This preference at the start of Sentence 7

But zoom out: the passage as a whole is about nothing.

Three things have gone wrong:

1. the subjects are unrelated (Portland, aroma, machines, dad, typewriter, I, preference);
2. the sentences share no common themes;
3. there's no thesis unifying the passage.

The key to coherence is consistent subjects.

When the subjects of your sentences name a small set of related characters, readers experience the passage as organized and focused.

But when the subjects shift randomly, readers experience confusion—even if each individual sentence is clear.

Why It Works

You can't assess the coherence of your own writing just by reading it. You know too much. You know how all the ideas connect, because you're the one who connected them.

But your readers don't have that advantage. They depend entirely on the signals you give them on the page.

The most powerful signal is the subject of each sentence.

Readers instinctively track subjects to figure out what a passage is about.

When they see a consistent set of subjects, their minds construct a coherent whole. But when the subjects jump around, readers feel lost. The writer might be able to see the underlying logic between these varying subjects. But there's nothing in the text that helps the reader see it.

This is why "vary your sentence openings" is dangerous advice.

Variation is fine in word choice. You can refer to the same thing with pronouns or synonyms—e.g., it, the company, and Acme Inc. all refer to the same entity.

But varying the topics of your subjects is a recipe for incoherence.

Many passages that seem disorganized can be fixed simply by making the subjects of sentences more consistent.

How to Use It