Progressive summarization: distill your notes in layers, one pass at a time

Progressive summarization is a technique for distilling notes in layers. You save the passages that struck you, and each time you come back to the note for real work, you add one more layer: bold the key sentences, highlight the best of those, write a short summary at the top. Over time, your most useful notes become the quickest to read, without you ever sitting down to summarize everything.

This guide covers the layers, the rule that makes the technique work, the common mistakes, and how to do it in Barside, a free desktop app for Windows, Linux and Mac.

What progressive summarization is

Tiago Forte of Forte Labs described the technique on December 27, 2017, in "Progressive Summarization: A Practical Technique for Designing Discoverable Notes". It later became the Distill step of his Building a Second Brain method, which runs Capture, Organize, Distill and Express.

The problem it solves is a tension every note-taker knows. A long note keeps the context you need to understand it later. A short note is fast to scan when you are in a hurry. Forte's answer is to balance discoverability against understanding: keep the full context, but add visible layers on top so the important parts jump out.

The second idea is timing. You do not summarize when you save something, because you do not yet know whether you will ever need it. You summarize when a project brings you back to the note.

The layers of progressive summarization

Forte numbers the layers from 0 to 5. Each is a smaller, sharper version of the one before.

Layer 0: the source

The original book, article, video, podcast or conversation. It stays where it is.

Layer 1: what you capture

The passages you save into your notes. Forte keeps "anything that feels insightful, interesting, or useful". This is not the whole article, only the parts that made you stop.

Layer 2: bold

On your first real pass, you bold the key words, phrases and sentences. This is the layer that lets you skim a note in seconds.

Layer 3: highlight

On a later pass, you highlight the "best of the best" among the bold parts. Only a few lines per note get this treatment.

Layer 4: summary

At the top of the note, you write a short executive summary in your own words. A few bullet points are enough. This is where you show yourself that you understood the source.

Layer 5: remix

For the most valuable sources only, you turn the material into something of your own: an essay section, a framework, a talk, a decision. Most notes never reach this layer, and they do not need to.

Summarize opportunistically

Forte's rule is to summarize "opportunistically": a little at a time, and only when you are already using a note for real work. That rule keeps the technique cheap.

Picture a note with twelve passages from an article on pricing. You saved it in March and forgot it. In June you are preparing a pricing proposal, so you open it, and while you read you bold the four sentences that matter. In September a client asks a pricing question, and this time you highlight one of the bold lines and add a two-line summary. Each visit took a minute, and each left the note better for the next one.

Notes you never return to stay at layer 1. That is not wasted effort. It is the technique working as designed, because you spent nothing on notes that turned out not to matter.

Common progressive summarization mistakes

• Compressing too much. A note cut down to a few words loses its meaning. You come back months later and cannot tell what the bold phrase was about. Keep enough context around the important parts.
• Compressing too little. If half the note is bold, nothing stands out, and the note is as hard to scan as before. Each layer should be much smaller than the one under it.
• Summarizing everything up front. Distilling every note on the day you save it costs hours and goes against the opportunistic rule.
• Capturing whole articles at layer 1. Saving everything means the later layers have to do the filtering you skipped. Capture the passages, not the page.
• Skipping your own words. A summary made of copied sentences is just another highlight. Layer 4 is where you rephrase.

How to do progressive summarization in Barside

Barside has the two things the technique needs: a reader where you can highlight while you read, and notes with bold and a highlight color. Both live in one library on your computer, with no account.

Layer 1: capture the passages

• Articles and newsletters. Save them to Reading: paste a link, or press Alt+Shift+Space in any app and choose Save to Reading. Select a passage and choose Highlight, or add a comment first. The Highlights list collects every highlight with its comment and the title it came from. See the read-it-later inbox with highlights.
• Books, talks and calls. Start a note from the Research notes template (Question, Sources, Findings, Next steps) and type or paste the passages under Findings.
• Text you cannot select. Press Alt+Shift+S and drag across a PDF page, a slide or a paused video. Barside reads the text on your computer and can add it to a note.

Make it a working note

When an article in Reading becomes part of a project, choose Keep as a note. It moves out of Reading into your notes, where you can format it, write around it and link it with [[. For a book or course, keep one note per source.

Layers 2 and 3: bold, then highlight

1. Open the note when a project needs it.
2. Select the key sentences and press Bold in the note toolbar.
3. On a later visit, select the best bold lines and pick a highlight color from the toolbar.

Use one highlight color for layer 3 across your whole library, so a highlighted line always means the same thing.

Layer 4: the summary at the top

Add a short heading such as Summary above the passages and write three to five bullets in your own words. If you connected an AI in Settings → AI, the assistant can edit a note in place and propose a summary, but treat it as a draft to rewrite. Barside has no AI of its own; it uses the Claude, ChatGPT, Gemini or OpenRouter account you connect.

To see at a glance which notes are fully distilled, give them a color of their own in Note options under Note color. Their cards and their dots on the note map then stand out from the rest.

Layer 5: the remix

Write the new piece in its own note: a proposal, a post, a lesson. Link each source with [[, so the source note's Linked from list shows where its ideas went. Next time you open the source, you see what you already made from it.

Find your distilled notes later

• The search bar. Press Alt+Shift+Space in any app, or Ctrl+K in Barside, and type a few words. It searches titles and text, so your summary words find the note.
• Ask library. In Library & briefing, ask a question and get an answer from your notes and Reading, with each source cited. A note with a clear summary at the top makes a better source. See AI search over your notes.

Who progressive summarization suits

• Writers and creators who build new work from what they read.
• Researchers and students who return to the same sources over months.
• Consultants and managers who reuse insights across clients and decisions.
• Heavy readers who highlight a lot and want those highlights to lead somewhere.

It suits people less if they rarely revisit notes, or if their notes are mostly short tasks and logistics. Then there is little to distill, and Getting Things Done may be the better fit.

Related methods

• Building a Second Brain, the full Capture, Organize, Distill and Express cycle.
• The PARA method, Forte's way to organize the notes you distill.
• Cornell note taking, cues, notes and a summary for lectures.
• The Zettelkasten method, rewriting each idea in your own words as its own linked note.