Flow: Connect Your Sentences with Old-Before-New

Someone once asked Elon Musk how he learns complicated topics so quickly.

It's important to view knowledge as a sort of tree. First, make sure you understand the trunk and big branches—the fundamental principles. Only then can you add the leaves and details, because without a strong trunk, there's nothing for them to hang on to.

Every new piece of information needs somewhere to attach. A leaf with no branch just falls.

Most writers never think about this—and it shows. When they want to improve their writing, they either jump straight to grammar rules or hand their writing off to AI. They never stop to ask: what does my reader actually need in order to understand this idea?

The answer is the same as Musk's.

Before you give a reader something new, you need to give them somewhere to hang it. Old information first—the trunk. New information second—the leaves.

Get that order right, and your writing flows. Get it wrong, and even grammatically perfect sentences feel like hard work.

So here's the principle: every sentence needs to give your reader two pieces of information, in the right order.

What It Is

To inform a reader, every sentence needs to deliver two things: 

1. old information (what the reader already knows)
2. new information (what the reader doesn't yet know).

But the order is important.

The principle of flow is simple: old before new.

Start each sentence with something familiar—a concept from the previous sentence, a term the reader already understands, a piece of context already established.

Then move to the new, complex, or unfamiliar material.

When you do this consistently, each sentence connects to the one before it. The old information at the beginning of sentence B picks up where sentence A left off. The writing flows.

When you reverse this—when you start with new, unfamiliar information and end with the familiar—readers feel lost. Each sentence feels disconnected from the last. That's giving readers the leaf of new information, and then asking them to find the trunk of context.

Why It Works

Think of it like a relay race: Each runner passes the baton to the next. If the baton gets dropped between runners, the race falls apart.

In writing, the "baton" is the concept that links one sentence to the next.

The end of one sentence introduces an idea; the beginning of the next sentence picks that idea up and carries it forward.

This aligns your text with the natural learning process of readers.

Readers build understanding cumulatively. They can't process new ideas in a vacuum. Before they can absorb a new idea, they need a foothold, something they already understand.

Old, familiar information provides that foothold.

Readers get familiar information from two sources:

1. Readers remember words from sentences they just read.

That's why the beginning of each new sentence can echo the end of the one before it:

2. Readers bring general knowledge of the subject to each new sentence.

Even a word that hasn't appeared yet won't feel surprising if it fits the topic:

Labor unions never appeared in the preceding sentences. But since we're reading about automation and manufacturing, the reference feels natural.

This is also why the passive voice sometimes produces clearer writing than the active voice.

If using the active voice forces new, complex information into the subject position, the sentence will feel harder to read—even though it follows the "rule" about active verbs. When a passive construction lets you start with familiar information and push the complexity to the end, it's the better choice.

How to Use It

Step 1: End sentences with information the next sentence can pick up. 

When you finish a sentence, the last significant concept should be something you'll develop next. The beginning of the following sentence should echo or refer back to it.

Here's an example. You need to fill in the blank:

Options:

1. The concentration of active users into a community perhaps no larger than a college campus triggers a network effect.
2. Network effects are triggered by the concentration of active users into a community perhaps no larger than a college campus.

Step 2: Use the beginning of each sentence to orient the reader. 

The first few words of your sentence should be the simplest, most familiar part. Use them to establish where you are in the conversation before delivering the new information.

Darwin is a character that will be familiar to most readers. Start with him.

Once the reader has a foothold with this familiar context, they'll be ready to process the complex, new details that unfold.

Step 3: Use introductory phrases to chain ideas. 

Short introductory clauses or prepositional phrases at the beginning of a sentence are powerful tools for connecting back to the previous sentence.

The introductory phrases (for increased strength, for increased flexibility) echo concepts from the end of the preceding sentence and orient the reader before the new details arrive.