Chapter 2 What Is a Second Brain?

We extend beyond our limits, not by revving our brains like a machine or bulking them up like a muscle—but by strewing our world with rich materials, and by weaving them into our thoughts.

—Annie Murphy Paul, author of The Extended Mind

Information is the fundamental building block of everything you do.

Anything you might want to accomplish—executing a project at work, getting a new job, learning a new skill, starting a business—requires finding and putting to use the right information. Your professional success and quality of life depend directly on your ability to manage information effectively.

According to the New York Times, the average person’s daily consumption of information now adds up to a remarkable 34 gigabytes.¹ A separate study cited by the Times estimates that we consume the equivalent of 174 full newspapers’ worth of content each and every day, five times higher than in 1986.²

Instead of empowering us, this deluge of information often overwhelms us. Information Overload has become Information Exhaustion, taxing our mental resources and leaving us constantly anxious that we’re forgetting something. Instantaneous access to the world’s knowledge through the Internet was supposed to educate and inform us, but instead it has created a society-wide poverty of attention.^I

Research from Microsoft shows that the average US employee spends 76 hours per year looking for misplaced notes, items, or files.³ And a report from the International Data Corporation found that 26 percent of a typical knowledge worker’s day is spent looking for and consolidating information spread across a variety of systems.⁴ Incredibly, only 56 percent of the time are they able to find the information required to do their jobs.

In other words, we go to work five days per week, but spend more than one of those days on average just looking for the information we need to do our work. Half the time, we don’t even succeed in doing that.

It’s time for us to upgrade our Paleolithic memory. It’s time to acknowledge that we can’t “use our head” to store everything we need to know and to outsource the job of remembering to intelligent machines. We have to recognize that the cognitive demands of modern life increase every year, but we’re still using the same brains as two hundred thousand years ago, when modern humans first emerged on the plains of East Africa.

Every bit of energy we spend straining to recall things is energy not spent doing the thinking that only humans can do: inventing new things, crafting stories, recognizing patterns, following our intuition, collaborating with others, investigating new subjects, making plans, testing theories. Every minute we spend trying to mentally juggle all the stuff we have to do leaves less time for more meaningful pursuits like cooking, self-care, hobbies, resting, and spending time with loved ones.

However, there’s a catch: every change in how we use technology also requires a change in how we think. To properly take advantage of the power of a Second Brain, we need a new relationship to information, to technology, and even to ourselves.

The Legacy of Commonplace Books

For insight into our own time, we can look to history for lessons on what worked in other eras. The practice of writing down one’s thoughts and notes to help make sense of the world has a long legacy. For centuries, artists and intellectuals from Leonardo da Vinci to Virginia Woolf, from John Locke to Octavia Butler, have recorded the ideas they found most interesting in a book they carried around with them, known as a “commonplace book.”^II

Popularized in a previous period of information overload, the Industrial Revolution of the eighteenth and early nineteenth centuries, the commonplace book was more than a diary or journal of personal reflections. It was a learning tool that the educated class used to understand a rapidly changing world and their place in it.

In The Case for Books,⁵ historian and former director of the Harvard University Library Robert Darnton explains the role of commonplace books:

Unlike modern readers, who follow the flow of a narrative from beginning to end, early modern Englishmen read in fits and starts and jumped from book to book. They broke texts into fragments and assembled them into new patterns by transcribing them in different sections of their notebooks. Then they reread the copies and rearranged the patterns while adding more excerpts. Reading and writing were therefore inseparable activities. They belonged to a continuous effort to make sense of things, for the world was full of signs: you could read your way through it; and by keeping an account of your readings, you made a book of your own, one stamped with your personality.^III

Commonplace books were a portal through which educated people interacted with the world. They drew on their notebooks in conversation and used them to connect bits of knowledge from different sources and to inspire their own thinking.

As a society, all of us could benefit from the modern equivalent of a commonplace book. The media landscape of today is oriented toward what is novel and public—the latest political controversy, the new celebrity scandal, or the viral meme of the day. Resurrecting the commonplace book allows us to stem the tide, shifting our relationship with information toward the timeless and the private.

Instead of consuming ever-greater amounts of content, we could take on a more patient, thoughtful approach that favors rereading, reformulating, and working through the implications of ideas over time. Not only could this lead to more civil discussions about the important topics of the day; it could also preserve our mental health and heal our splintered attention.

But this isn’t simply a return to the past. We now have the opportunity to supercharge the custom of commonplace books for the modern era. We have the chance to turn that historical practice into something far more flexible and convenient.

The Digital Commonplace Book

Once our notes and observations become digital, they can be searched, organized and synced across all our devices, and backed up to the cloud for safekeeping. Instead of randomly scribbling down notes on pieces of paper, hoping we’ll be able to find them later, we can cultivate our very own “knowledge vault” so we always know exactly where to look.

Writer and photographer Craig Mod wrote, “There is a gaping opportunity to consolidate our myriad marginalia^IV into an even more robust commonplace book. One searchable, always accessible, easily shared and embedded amongst the digital text we consume.”⁶

This digital commonplace book is what I call a Second Brain. Think of it as the combination of a study notebook, a personal journal, and a sketchbook for new ideas. It is a multipurpose tool that can adapt to your changing needs over time. In school or courses you take, it can be used to take notes for studying. At work, it can help you organize your projects. At home, it can help you manage your household.

However you decide to use it, your Second Brain is a private knowledge collection designed to serve a lifetime of learning and growth, not just a single use case. It is a laboratory where you can develop and refine your thinking in solitude before sharing it with others. A studio where you can experiment with ideas until they are ready to be put to use in the outside world. A whiteboard where you can sketch out your ideas and collaborate on them with others.

As soon as you understand that we naturally use digital tools to extend our thinking beyond the bounds of our skulls, you’ll start to see Second Brains everywhere.

A calendar app is an extension of your brain’s ability to remember events, ensuring you never forget an appointment. Your smartphone is an extension of your ability to communicate, allowing your voice to reach across oceans and continents. Cloud storage is an extension of your brain’s memory, allowing you to store thousands of gigabytes and access them from anywhere.^V

It’s time to add digital notes to our repertoire and further enhance our natural capabilities using technology.

Rethinking Notetaking: Notes as Knowledge Building Blocks

In past centuries, only the intellectual elite needed commonplace books—writers, politicians, philosophers, and scientists who had a reason to synthesize their writing or research.

Nowadays, almost everyone needs a way to manage information.

More than half the workforce today can be considered “knowledge workers”—professionals for whom knowledge is their most valuable asset, and who spend a majority of their time managing large amounts of information. In addition, no matter what our formal role is, all of us have to come up with new ideas, solve novel problems, and communicate with others effectively. We have to do these things regularly, reliably, not just once in a while.

As a knowledge worker, where does your knowledge live? Where does your knowledge go when it’s created or discovered? “Knowledge” can seem like a lofty concept reserved exclusively for scholars and academics, but at the most practical level, knowledge begins with the simple, time-honored practice of taking notes.

For many people, their understanding of notetaking was formed in school. You were probably first told to write something down because it would be on the test. This implied that the minute the test was over, you would never reference those notes again. Learning was treated as essentially disposable, with no intention of that knowledge being useful for the long term.

When you enter the professional world, the demands on your notetaking change completely. The entire approach to notetaking you learned in school is not only obsolete, it’s the exact opposite of what you need.

In the professional world:

• It’s not at all clear what you should be taking notes on.
• No one tells you when or how your notes will be used.
• The “test” can come at any time and in any form.
• You’re allowed to reference your notes at any time, provided you took them in the first place.
• You are expected to take action on your notes, not just regurgitate them.

This isn’t the same notetaking you learned in school. It’s time to elevate the status of notes from test prep and humble scribblings into something far more interesting and dynamic. For modern, professional notetaking, a note is a “knowledge building block”—a discrete unit of information interpreted through your unique perspective and stored outside your head.

By this definition, a note could include a passage from a book or article that you were inspired by; a photo or image from the web with your annotations; or a bullet-point list of your meandering thoughts on a topic, among many other examples. A note could include a single quote from a film that really struck you, all the way to thousands of words you saved from an in-depth book. The length and format don’t matter—if a piece of content has been interpreted through your lens, curated according to your taste, translated into your own words, or drawn from your life experience, and stored in a secure place, then it qualifies as a note.

A knowledge building block is discrete. It stands on its own and has intrinsic value, but knowledge building blocks can also be combined into something much greater—a report, an argument, a proposal, a story.

Like the LEGO blocks you may have played with as a kid, they can be rapidly searched, retrieved, moved around, assembled, and reassembled into new forms without requiring you to invent anything from scratch. You need to put in the effort to create a note only once, and then you can just mix and match and try out different combinations until something clicks.

Technology doesn’t just make notetaking more efficient. It transforms the very nature of notes. No longer do we have to write our thoughts on Post-its or notepads that are fragile, easy to lose, and impossible to search. Now we write notes in the cloud, and the cloud follows us everywhere. No longer do we have to spend countless hours meticulously cataloging and transcribing our thoughts on paper. Now we collect knowledge building blocks and spend our time imagining the possibilities for what they could become.

A Tale of Two Brains

Let me paint a picture of a day in the life of someone who doesn’t have a Second Brain, and someone who does. See if either of these descriptions sounds familiar.

Nina wakes up on Monday morning, and before her eyes even open, thoughts are flooding her brain. Things to do, things to think about, things to decide. It all comes rushing in from the depths of her subconscious, where it’s been simmering all weekend.

Nina’s thoughts continue to swirl around her brain as she gets ready for work. Like jittery birds, they flit and flutter around her head because they have nowhere else to rest. There is a constant hum of background anxiety that she has come to expect, as she wonders what needs her attention and what she may be missing.

After a hectic morning, Nina finally sits down at her desk to start her workday, opens up her email inbox, and is instantly engulfed by a torrent of new messages. Flashing with urgent subject lines and the names of important senders, these demands fill her with a cold adrenaline rush. She knows that her morning is shot, her own plans ruined. Pushing aside the important work she wanted to focus on this morning, Nina settles in for a long slog of replying to emails.

By the time she gets back from lunch, Nina is finally done handling the most urgent issues. It’s finally time to focus on the priorities she’s set for herself. This is when the reality sets in: after a morning spent fighting fires, she’s far too scatterbrained and tired to focus. Like so many times before, Nina lowers her expectations, settling for chipping away slowly at her ever-expanding to-do list full of other people’s priorities.

After work, Nina has one last chance to work on the project that she knows will make use of her talents and take her career to the next level. She exercises, eats dinner, and spends some quality time with the kids. As they go to bed, she’s filled with enthusiasm that she finally gets some time to herself.

She sits down at the computer, and the questions begin: “Where did I leave off last time? Where did I put that file? Where are all my notes?”

By the time Nina gets set up and ready to go, she’s far too tired to make real progress. This pattern repeats itself day after day. After enough of these false starts, she starts to give up. Why even try? Why keep attempting to do the impossible? Why resist the temptation to watch another Netflix episode or scroll through social media? Without the time and energy to move things decisively forward, what’s the point of starting?

Nina is a competent, responsible, and hardworking professional. Many people would feel privileged to be in her shoes. There’s nothing wrong with the work she does or the life she leads, yet underneath the respectable exterior, there is something missing. She isn’t meeting her own standards for what she knows she’s capable of. There are experiences that she wants for herself and her family that seem to continuously get postponed, waiting for “someday” when somehow she will have the time and space to make them happen.

Does anything about Nina’s experience sound familiar? Every detail of her story is real, drawn from messages people have sent me over the years. Their stories convey a pervasive feeling of discontent and dissatisfaction—the experience of facing an endless onslaught of demands on their time, their innate curiosity and imagination withering away under the suffocating weight of obligation.

So many of us share the feeling that we are surrounded by knowledge, yet starving for wisdom. That despite all the mind-expanding ideas we have access to, the quality of our attention is only getting worse. That we are paralyzed by the conflict between our responsibilities and our most heartfelt passions, so that we’re never quite able to focus and also never quite able to rest.

There is an alternative story. A different way a Monday morning can go. It is also drawn from the real-life stories I’ve received, this time from people who have built a Second Brain for themselves.

You wake up Monday morning, looking forward to starting your day and your week. As you get out of bed, take a shower, and get dressed, the thoughts start arriving. You have just as many worries and responsibilities as anyone else, but you also have a secret weapon.

In the shower, you suddenly realize there’s a better way to advance the project you’re focused on at work. As you step out onto the mat, you jot down the idea as a digital note on your smartphone. Over breakfast with your family, you find your mind already working out the new strategy, pondering its implications. Those thoughts get jotted down as well, in the brief moments between feeding the kids and sending them off to school. As you drive to work, you start realizing there are challenges you haven’t considered. You dictate a quick audio memo to your phone as you drive, which gets automatically transcribed and saved in your notes.

Monday morning in the office is the usual whirlwind, with emails and chat messages and phone calls arriving at their usual frantic pace. As you share your new idea with your colleagues, they start asking questions, pointing out valid concerns, and adding their own contributions. At each of these moments, you are ready to save them as notes in your Second Brain. You withhold judgment, seeking to gather the widest possible range of feedback before deciding on a course of action.

Before you know it, it’s lunchtime. As you take a break to grab a bite to eat, your thoughts turn philosophical: “What is the ultimate point of the project, and are we forgetting it? How does it fit into the long-term vision of the product we want to build? What is the impact of the new strategy on shareholders, customers, suppliers, and the environment?” You have only thirty minutes to eat lunch, and you don’t have time to ponder these questions in depth, but you note them down as a reminder to think about later.

You are on your smartphone just like everyone else, but you aren’t doing what they are doing. You are creating value instead of killing time.

By the time the afternoon meeting comes around to review the strategy you’ve come up with, you already have a formidable collection of notes ready and waiting: the ideas, strategies, objectives, challenges, questions, concerns, contributions, and reminders you’ve collected over just a few hours on a Monday morning.

You take ten minutes before the meeting starts to organize your notes. About a third of them aren’t a priority, and you put them aside. Another third are critical, and you make them into an agenda for the meeting. The remaining third are somewhere in between, and you put them into a separate list to refer to if appropriate.

As the meeting begins, the team sits down to start discussing the project. You are already prepared. You’ve already considered the biggest problems from several different angles, mapped out a number of possible solutions, and started thinking about the big-picture implications. You’ve even received feedback from some of your colleagues and incorporated it into your recommendations. You argue for your point of view while also remaining open to the perspectives of your team. Your goal is to stay present and guide the conversation to the best possible outcome, making use of everyone’s unique way of seeing things. All the important reflections, new ideas, and unexpected possibilities your colleagues come up with also get recorded in your Second Brain.

As this way of working with information continues over days and weeks and months, the way your mind works begins to change. You start to see recurring patterns in your thinking: why you do things, what you really want, and what’s really important to you. Your Second Brain becomes like a mirror, teaching you about yourself and reflecting back to you the ideas worth keeping and acting on. Your mind starts to become intertwined with this system, leaning on it to remember more than you ever could on your own.

All this is literally not just in your head. People can tell there is something different about you. They start to recognize that you can draw on an unusually large body of knowledge at a moment’s notice. They remark on your amazing memory, but what they don’t know is that you never even try to remember anything. They admire your incredible dedication to developing your thinking over time. In reality, you are just planting seeds of inspiration and harvesting them as they flower.

As you begin to see all the knowledge you’ve gained in tangible form, it dawns on you that you already have everything you need to strike out toward the future you want. There’s no need to wait until you’re perfectly prepared. No need to consume more information or do more research. All that’s left is for you to take action on what you already know and already have, which is laid out before you in meticulous detail.

Your brain is no longer the bottleneck on your potential, which means you have all the bandwidth you need to pursue any endeavor and make it successful. This sense of confidence in the quality of your thinking gives you the freedom to ask deeper questions and the courage to pursue bigger challenges. You can’t fail, because failure is just more information, to be captured and used as fuel for your journey.

This is what it’s like to build and harness the power of a Second Brain.

Leveraging Technology as Thinking Tools

Throughout the twentieth century, a series of scholars and innovators⁷ offered a vision for how technology could change humanity for the better. They dreamed of creating an “extended mind” that would amplify human intellect and help us solve the greatest problems facing society.^VI The possibility of such a technological marvel shined like a beacon for the future, promising to liberate knowledge from dusty old books and make it universally accessible and useful.^VII

Their efforts were not in vain. Those ideas inspired much of the technology that we use every day, but paradoxically, despite all the technological inventions of the Information Age, we are in some ways further from their original vision than ever. We spend hours every day interacting with social media updates that will be forgotten in minutes. We bookmark articles to read later, but rarely find the time to revisit them again. We create documents that are used once and then get abandoned in the abyss of our email or file systems. So much of our intellectual output—from brainstorms to photos to planning to research—all too often is left stranded on hard drives or lost somewhere in the cloud.

I believe that we have reached an inflection point, where technology has become sufficiently advanced and user-friendly that we can integrate it with our biological brains. Computers have become smaller, more powerful, and more intuitive, to the point that they are unmistakably an essential component of how we think.

The time has come for us to realize the vision of technology’s early pioneers—that everyone should have an extended mind not just to remember more and be more productive, but to lead more fulfilling lives.

1. I. Herbert Simon, an American economist and cognitive psychologist, wrote, “What information consumes is rather obvious: it consumes the attention of its recipients. Hence a wealth of information creates a poverty of attention…”
2. II. The word “commonplace” can be traced back to Ancient Greece, where a speaker in law courts or political meetings would keep an assortment of arguments in a “common place” for easy reference.
3. III. The practice of keeping personal notes also arose in other countries, such as biji in China (roughly translated as “notebook”), which could contain anecdotes, quotations, random musings, literary criticism, short fictional stories, and anything else that a person thought worth recording. In Japan, zuihitsu (known as “pillow books”) were collections of notebooks used to document a person’s life.
4. IV. “Marginalia” refers to the marks made in the margins of a book or other document, including scribbles, comments, annotations, critiques, doodles, or illustrations.
5. V. Have you ever lost your smartphone or been unable to access the Internet, and felt like a critical part of yourself was missing? That’s a sign that an external tool has become an extension of your mind. In a 2004 study, Angelo Maravita and Atsushi Iriki discovered that when monkeys and humans consistently use a tool to extend their reach, such as using a rake to reach an object, certain neural networks in the brain change their “map” of the body to include the new tool. This fascinating finding reinforces the idea that external tools can and often do become a natural extension of our minds.
6. VI. Recent advancements and discoveries in the field of “extended cognition” have shed new light on how practical and powerful it can be to “think outside the brain.” This book isn’t focused on the science, but for an excellent introduction to extended cognition I recommend The Extended Mind by Annie Murphy Paul.
7. VII. Vannevar Bush wrote of a “scholar’s workstation” called a “Memex,” which was “a device in which an individual stores all his books, records, and communications, and which is mechanized so that it may be consulted with exceeding speed and flexibility. It is an enlarged intimate supplement to his memory.”