Building a second brain, the simple version

What a second brain is, in Tiago Forte’s words

Tiago Forte taught his method as an online course before publishing Building a Second Brain in 2022. He describes a second brain as an external, centralised, digital repository for the things you learn and the resources they come from.

The workflow is CODE:

1. Capture. Save what resonates with you. Forte tells readers to think like a curator: keep what strikes you, not everything that passes by.
2. Organize. Sort by what you’ll act on, not by subject. That’s what PARA is for.
3. Distill. Summarise in layers over time. Forte calls this Progressive Summarization: each time you revisit a note, you highlight a little more, so the key point can be found in seconds.
4. Express. Use what you saved to make something: a report, a talk, a decision.

The filing system is PARA:

The clever part of PARA is filing by when you’ll need it next rather than by a big tree of topics. In the book, Forte adds three habits: checklists for projects you repeat, weekly and monthly reviews, and small tidy-ups when you happen to open a note.

Before apps: Luhmann’s 90,000 cards

Long before Notion and Obsidian, the German sociologist Niklas Luhmann kept a paper Zettelkasten, or slip box. According to Bielefeld University, which holds his papers, it contains about 90,000 notes written between 1951 and 1996. His output was nearly 600 publications, including more than 40 books.

The mechanics were simple and strict. Every card got a fixed number. A thought that continued an earlier card got that card’s number plus a letter and was filed right behind it, so chains of ideas branched inward. Cross-references linked distant cards, and a keyword index gave a few entry points. There was no master outline; the box grew from the inside.

Here’s the honest lesson. Luhmann’s system served one job, producing theory, and he fed it for 45 years. If your goal is to remember your mother-in-law’s birthday and find your car insurance number, a slip box is the wrong tool. Plenty of online advice treats “second brain” and “Zettelkasten” as the same thing. They aren’t.

What memory research says about offloading

Psychologists call it cognitive offloading: using a physical action or a tool to reduce the mental effort of a task, like setting a phone reminder for an appointment. Evan Risko and Sam Gilbert reviewed the field in Trends in Cognitive Sciences in 2016. Their framework puts metacognition at the centre: we offload based on what we believe about our own memory, and those beliefs can be wrong.

Reminders work. In four online experiments (N = 1,196), Sam Gilbert of University College London found that setting external reminders improved performance on delayed intentions. People set more reminders when they had more to remember or were likely to be distracted, and older participants used them more. This is prospective memory, remembering to do something later, which is what these experiments measured.

Saving frees up space. Benjamin Storm and Sean Stone (2015, Psychological Science) found in three experiments that saving one file before studying another improved memory for the second. The benefit vanished when people were told the save might not work. A system you don’t trust doesn’t lighten the load.

But you remember less of what you hand over. Betsy Sparrow, Jenny Liu and Daniel Wegner’s 2011 Science paper, the source of the “Google effect”, reported that when people expect future access to information, they recall the information less and where to find it more. Treat it with care. In 2018, Colin Camerer and colleagues re-ran 21 social-science experiments from Nature and Science; 13 replicated. The Sparrow test, of the paper’s first experiment (whether hard trivia questions make people think of computers), did not. A 2024 meta-analysis by Gong and Yang concludes the effect is real but depends on context, such as cognitive load and whether people search on a phone or a computer. In a related study, Linda Henkel (2014) found that people on a guided museum tour remembered fewer objects they had photographed whole than objects they had only looked at.

The practical rule: give your second brain what you need to find again (dates, numbers, documents, commitments), and keep in your head what you want to know (your craft, a language, your colleagues’ names).

The simple version: one inbox, four places

A second brain that lasts is one you use without thinking. Four places cover most of life, each for one kind of information.

Add an inbox: one place where everything lands during the day, unsorted. A phone note, a notebook or your assistant. Sorting later is what lets you capture in two seconds.

Start with reminders; that’s where the evidence is most direct. For tasks, see our guide on how to make a to-do list; for paper, how to organize paperwork.

The 15-minute weekly review

This lines up with the weekly review Forte recommends. If you already use a weekly planner, run the review first and plan second.

What’s overkill

The classic trap is building a cathedral you then don’t have time to maintain. You can safely skip:

• Linking every note to every other note. Great for writing a book the Luhmann way, pointless for running a household.
• Dozens of tags. If you can’t decide between three tags, you won’t find the note later. Project or topic folders are enough.
• Capturing everything. Forte’s own advice is to keep what resonates. A read-later list you never read is guilt, not memory.
• Summarising every note up front. Progressive Summarization is meant to happen when you revisit a note, not in advance.
• Switching apps every quarter. Migrating costs hours and fixes nothing. Knowing where each kind of information goes matters more than features.
• Storing passwords in it. A notes app isn’t a vault; use a password manager. See our guide to a digital vault for important documents.

With Binome360: say it instead of filing it

Binome360 covers two of the four places in one sentence. Say “remember that…” and it keeps the fact in your memory and gives it back when you ask. Say “remind me…” and it prepares a one-off or recurring reminder. Files can be attached to your records, and in a shared assistant for your household, everyone adds from their own phone.

It isn’t a note-taking tool for writing a thesis. It’s the simple version: the dates and facts of everyday life, handed over by talking.

Frequently asked questions

What is the best app for a second brain?

The one you already open every day. For most people, a notes app, a calendar with reminders and a well-named files folder are enough. What matters is knowing where each kind of information goes, not the feature list.

What’s the difference between a Zettelkasten and a second brain?

Luhmann’s Zettelkasten is a network of linked cards built to generate ideas and writing. Forte’s second brain is broader: it files all useful information by your projects and areas of life. The first is mainly for thinking; the second is mainly for finding and acting.

Does a second brain make your memory worse?

You do tend to remember less of what you offload, which is what the Google effect and museum-photo studies point to, even though the best-known Google effect test failed to replicate. Offload dates and practical facts; keep learning the things that matter to you.

How much time does a second brain take?

A few seconds to capture, and about 15 minutes a week to sort. If your system needs more than an hour a week of upkeep, it’s too complicated.

In short

A useful second brain is not a library. It’s one inbox, four places (reminders, memory, documents, projects) and a 15-minute weekly review. Research supports reminders for following through on intentions, as long as you trust the system and don’t offload what you actually want to learn.

First action: write down the three things you’re most afraid of forgetting this week, and turn each one into a dated reminder.

Sources

• Tiago Forte, Building a Second Brain, Simon & Schuster, 2022.
• Forte Labs, “Building a Second Brain: The Definitive Introductory Guide”: fortelabs.com/blog/basboverview; “The PARA Method”: fortelabs.com/blog/para.
• Bielefeld University, Niklas Luhmann Archive: uni-bielefeld.de/fakultaeten/soziologie/forschung/luhmann-archiv.
• University of Cologne, “Die Denkmaschine” (how the Zettelkasten worked): uni-koeln.de.
• Evan F. Risko and Sam J. Gilbert, “Cognitive Offloading”, Trends in Cognitive Sciences, 20(9), 676–688, 2016: doi.org/10.1016/j.tics.2016.07.002.
• Sam J. Gilbert, “Strategic offloading of delayed intentions into the external environment”, Quarterly Journal of Experimental Psychology, 68(5), 971–992, 2015: doi.org/10.1080/17470218.2014.972963.
• Benjamin C. Storm and Sean M. Stone, “Saving-enhanced memory”, Psychological Science, 26(2), 182–188, 2015: doi.org/10.1177/0956797614559285.
• Betsy Sparrow, Jenny Liu and Daniel M. Wegner, “Google Effects on Memory”, Science, 333(6043), 776–778, 2011: doi.org/10.1126/science.1207745.
• Colin F. Camerer et al., “Evaluating the replicability of social science experiments in Nature and Science between 2010 and 2015”, Nature Human Behaviour, 2, 637–644, 2018: doi.org/10.1038/s41562-018-0399-z.
• C. Gong and Y. Yang, “Google effects on memory: a meta-analytical review of the media effects of intensive Internet search behavior”, Frontiers in Public Health, 12, 2024: doi.org/10.3389/fpubh.2024.1332030.
• Linda A. Henkel, “Point-and-shoot memories”, Psychological Science, 25(2), 396–402, 2014: doi.org/10.1177/0956797613504438.

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