A Second Brain Was Supposed to Be "Jarvis"

You use the term "second brain" all the time, but do you know where it came from?

It hasn't been around long. A guy named Tiago Forte started teaching a course called Building a Second Brain back in 2017, and that's really where the phrase starts. The course began almost funny in how small it was. He was teaching people how to keep Evernote tidy without burying everything under a pile of tags. That was the whole pitch. The thing only blew up years later, in 2022, when Forte turned it into a book that hit the Wall Street Journal bestseller list and put "second brain" into everybody's vocabulary.

The idea was never new, though. Forte basically gave a fresh name to something people had been calling Personal Knowledge Management, or PKM, since the late 90s, after a couple of researchers named Frand and Hixon first wrote the term down. And the urge behind it runs much deeper than any of these names. People kept commonplace books for centuries, copying out quotes and passages they didn't want to lose. We've always made more than our heads can hold, so we've always built something on the outside to catch what spills over.

Then the tools caught up. Evernote, Notion, Roam, Obsidian, each arriving in its own time, the later ones landing right as the second brain idea was catching fire. They fit it perfectly, because they did the obvious things you'd want done. They held your stuff, linked it together, let you search it, kept it in order. So that's quietly what a second brain turned into for most people. A really well-organized version of what they already knew. Notes, backlinks, databases, dashboards, all polished up.

And people went all in. Notion crossed 100 million users by early 2026 and got valued at 10 billion dollars, with Fortune 500 teams running on it. Obsidian, with no investors and no funding at all, grew to around 1.5 million monthly users who care enough about owning their own notes to build entire systems by hand. Forte's book sold half a million copies in more than 25 languages. A whole corner of the internet turned into people teaching other people how to build the perfect setup, with the YouTube tutorials and the template shops and the Discord servers to match. The second brain clearly struck a nerve. It answered something real, that very old fear of knowing something once and never finding it again. By every measure the people building these systems care about, it works.

Hang around the second-brain crowd long enough and you'll notice the conversation isn't only about tools. It's about friction. People argue over whether any of this actually works. They complain that the systems get too heavy to maintain. A lot of them end up calling their setups beautiful graveyards, gorgeous to look at and impossible to keep alive once the novelty wears off.

Push those complaints far enough and they all land on the same handful of questions. How do I stop spending more time tending the system than using it? How do I find things again without digging? How do I keep this from rotting into an archive I never open?

AI walked right into that opening. If the problem is that your knowledge sits there static and manual and hard to reach when you actually need it, then of course an assistant that can search, summarize, and pull up the right note on demand looks like the fix. That's where most of the energy in the PKM world has gone lately. Just inside Obsidian you've got Smart Connections surfacing related notes as you write, Copilot for Obsidian answering questions across your whole vault, Smart Composer and a dozen others all chasing the same thing: make the notes easier to query, easier to connect, easier to actually use.

You can see the same turn at the community level. The European PKM Summit, the field's main gathering, now runs sessions like OpenClaw: Personal AI Agents Transform PKM Today and Robots in the Garden: Using AI to Augment Your Thinking. A few years ago the AI talks were a side track. Now they're the main stage, and nobody finds that surprising anymore.

The direction makes sense, and honestly it's the right one. AI does make these systems faster to search, lighter to maintain, easier to lean on. But it also throws the real gap into sharp relief.

Because almost everything the ecosystem is doing with AI starts from the same raw material. Your notes. Your saved articles. Your highlights. The stuff you deliberately wrote down. AI is making that knowledge layer smarter and more alive, no question. It's just that a livelier knowledge base still isn't the same as one that knows you.

And that's the thing. A second brain was never supposed to be a livelier knowledge base. It was supposed to be Jarvis.

Jarvis was never impressive because it knew more facts than anyone else. What made it feel like magic was that it knew Tony. It knew how he worked, what he'd reach for, what he'd brush off, the call he'd make before he made it. It didn't just hold information. It held a person.

That's the part the whole conversation keeps walking past. A system built only on notes can know the version of you that you chose to write down, and not an inch more. What you saved, what you highlighted, what you decided was worth keeping. But that's the edited you. The deliberate you. Most of the time it's closer to the person you're trying to become than the one you already are.

The actual you doesn't live there. It lives in what you go back to without meaning to, what you linger on, what you scroll past, what you do when nobody's keeping score. Your notes show how you think. Your behavior shows how you live. Those are not the same thing, and a system that only ever sees the first one is always going to be missing half the picture.

So the missing layer was never more knowledge. It was you, the real one.

Put it plainly. A real second brain runs on three things. Your notes, which carry how you think. Your behavior, which carries who you actually are. And an agent that can act on both. Almost everyone already has the notes. The agent is showing up fast. The piece in the middle, the real you, is the one that's been missing the entire time, and it's the piece that decides whether you end up with a very tidy archive or something that finally knows who it's working for.

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