THE COMMONPLACE
BOOK.

Four centuries of people writing down what mattered to them. From John Locke’s indexing system to Tiago Forte’s digital repackaging.

The question never changes… what’s worth keeping?

A commonplace book isn’t a diary. A diary is where you put your day. A commonplace book is where you put everyone else’s best thinking, copied out in your own hand because it was too good to lose. A line from a novel. A definition that finally made something click. A sentence you wished you had said.

You collect the borrowed brilliance, and somewhere in the collecting, the choices start to add up to a portrait of you.

I keep one. Not because a productivity person told me to, although several have tried. I keep one because I’m an audiobook person who still needs somewhere for the good parts to land. Listening is intake. The commonplace book is where intake becomes unique thoughts I log as valuable to me.

I assumed this was a hobbyist thing, a recent invention of the journaling aisle. It’s roughly five hundred years old, and the people who kept these books weren’t dabbling.

In 1512 the humanist Erasmus told students, in a book called De Copia, to keep a notebook divided by topic-headings, a place to store the lines worth reusing. He took his own advice to a degree that should make every note-taking app blush. He carted his collected passages around in actual boxes, organized by theme, and when he sat down to write something new he would go through the relevant box and cross each note out as he used it.

A second brain in a literal crate.

The idea was older than him too. Cicero called these saved passages loci communes, the common places, the lines a thinking person kept on hand. So the habit I thought I’d picked up from a stationery shelf had been sitting in scholars’ boxes since before Shakespeare.

The unglamorous truth: collecting is the fun part. The trouble has always been the same trouble I have with my own notes. You write the perfect thing down and then you can never find it again.

John Locke, the philosopher, was apparently as annoyed by this as I am. He worked out an indexing system and published it, in French in 1686 and in English in 1706, under the very plain title A New Method of a Common-Place-Book. His fix was a small index where you filed each entry by its first letter and the first vowel that followed. Tedious by my standards. But look at what it admits.

The bottleneck was never collecting. It was retrieval.

Even three hundred years ago, with a fraction of the information I drown in daily, it was knowing what you had and being able to put your hand on it.

Fast forward. The commonplace book got a rebrand. Tiago Forte called it a second brain and built a whole method around it. Notion, Obsidian, Evernote, a thousand templates and a monthly fee. I’m not knocking it, I live in those tools. But it’s worth saying plainly that the productivity industry didn’t invent this. It repackaged a five-hundred-year-old habit, added sync and sold it back to us as a revelation.

The bones are identical. Capture what matters. Organize it so you can find it. Use it to make something new. Erasmus did it with boxes. Locke did it with an index. I do it with a dotted notebook and, lately, an app I pay for.

Four centuries, one habit, better packaging.

This old little book matters more to me now than it ever has.

The machines I work with all day can collect infinitely. They never forget, never run out of boxes, never lose the note. If accumulation were the point, the contest is over and the humans lost decades ago.

But accumulation was never the point. The commonplace book doesn’t ask what can I save. It asks what’s worth keeping. And that’s a different kind of question. It’s a judgment. A small, repeated act of deciding this line matters and that one doesn’t. Every entry is me saying out loud that I’m still the one choosing.

That’s the part no machine can do for me without becoming me. An AI can hand me ten thousand quotes on any subject in a second.

It can’t tell me which one I’ll still believe in a year.

The keeping is mine. The choosing is mine. In a year where I handed a lot of thinking over to faster tools, the commonplace book is the one place I still sit down and decide, by hand, what’s worth carrying forward. What would it cost to let something else decide that for me? I’m not willing to find out.

The dotted notebook, the good pen and the correction tape were never really about stationery. Each one was a small thing from the supply closet that turned out to be the same quiet act… choosing for myself instead of letting the default choose for me.