The Locksmith's Touch: On John Locke's Method for Commonplacing

Our current obsession with digital note-taking apps, with their promises of infinite connectivity and frictionless recall, feels remarkably new. But the urge to manage personal knowledge, to build a second memory outside the skull, is ancient. And some of the most elegant systems were designed not for servers, but for vellum and ink. Among the most influential belongs to a man better known for his thoughts on government and the self: the 17th-century philosopher John Locke.

In 1685, two decades before he would shape Enlightenment politics, Locke wrote a six-page letter to a friend. Its title was unassuming: "A New Method of a Common-Place-Book." Commonplace books—bound volumes where one collected quotes, observations, and ideas—were the personal knowledge management (PKM) tools of the educated elite. The problem, as Locke saw it, was retrieval. A haphazard collection of brilliant passages was a locked chest without a key. You might remember a stunning line from Seneca, but was it under "V" for virtue, "A" for anger, or "M" for mortality? The chaos of memory began to infect the archive itself.

A Mechanical Index for an Organic Mind

Locke’s solution was a system of breathtaking, almost bureaucratic, simplicity. He proposed a two-part apparatus: the blank book for entries, and an alphabetized index at the back. The innovation was in the index's structure. Instead of listing page numbers under topic headings, which forced you to pre-judge a quote's ultimate category, Locke's index worked via combinatorial codes.

Each page of the commonplace book was assigned a number. On the index page, for a topic like "Electricity," you wouldn't write "pp. 12, 45, 78." Instead, you would note the first letter of the first word of each relevant entry on those pages, followed by the page number. So you might see: "Electricity: a12, t45, o78." To find all entries on a topic, you scanned the index, then flipped to the noted pages, glancing only at entries beginning with the specified letter. It was a manual search algorithm, leveraging the physical fact of the initial letter as a unique identifier to filter noise.

The system's genius was its flexibility and its acknowledgment of forgetting. You didn't need perfect foresight. When you copied a passage, you gave it a simple, obvious keyword—say, "Ephemera." Then you went to the index, found "Ephemera," and added the code for your new entry. If you later realized the same quote also spoke to "Beauty," you simply added another code under "Beauty" in the index. The entry itself never moved. It sat in one place, but it could be found via multiple conceptual paths.

Locke wasn't just organizing notes; he was modeling how thought branches and associates. His method externalized the mind's tendency to link a single observation to multiple themes. It created a static repository with a dynamic, user-updatable map. In our terms, he separated data storage from metadata, allowing the latter to evolve without disrupting the former.

There's a quiet lesson here for our digital gardens. We chase the magic of bi-directional links and AI tags, hoping the tool itself will reveal connections we cannot see. Locke’s method reminds us that the deepest value lies not in automated complexity, but in the deliberate, iterative act of curation—the locksmith's touch of assigning a key, and then another, knowing the treasure within can be unlocked in more than one way. Our feeds and notes may be infinite, but the real work remains the same: to build a index for our future, forgetful selves.

Notes & further reading

A few pages I came back to while writing this: