The Commonplace Cavalry: On the 17th-Century Hack That Saved a Revolution
We often imagine the tools of thought—our note-taking apps, our curated feeds—as modern inventions, digital salves for a uniquely digital age. But the human struggle to manage a flood of information, to separate signal from noise, and to marshal fragments of thought into coherent action is ancient. Sometimes, the most powerful personal knowledge management system isn't an app at all, but a simple, disciplined habit. And sometimes, its success can change the course of history.
Consider the case of John Locke, not just the philosopher, but the physician and political operative. In 1660, as a young Oxford scholar, he began a methodical project that would last his entire life: a series of elaborate commonplace books. But Locke’s system was a radical departure from the haphazard journals of his contemporaries. He wasn’t just collecting thoughts; he was engineering a retrieval system.
His innovation was an index. Not a simple list of topics, but a complex, two-stage taxonomic key. He first reserved several pages at the back of each notebook, labeling them with letters of the alphabet. Under each letter, he listed broad topics (‘Aristotle’, ‘Bible’, ‘Travel’). Next to each topic, he didn’t write a page number. Instead, he assigned the topic a number. Then, on the actual pages of the notebook, where he entered his quotes and observations, he would write these assigned numbers in the margin next to the relevant entry.
This meant that to find every note he’d ever made on, say, ‘Toleration’, he would go to the index, find the topic’s assigned number (e.g., 36), and then flip through the entire notebook, scanning the margins for that number. It was a system designed for serendipitous rediscovery, forcing a re-reading of adjacent notes and fostering new connections. He was, in effect, manually running a search query across the analog database of his own mind.
This was more than an academic exercise. Decades later, while in exile in Holland, Locke was the intellectual engine of the revolutionary movement plotting to overthrow King James II. His task was to synthesize a vast array of historical precedents, legal arguments, and philosophical principles into a coherent justification for action. The revolution’s public relations campaign—the pamphlets, the manifestos—depended on his ability to quickly access and cross-reference a lifetime of reading.
The Glorious Revolution of 1688 succeeded. William of Orange took the throne, and Locke returned to England a hero. His subsequent works, including the foundational Two Treatises of Government, were built upon the bedrock of those meticulously indexed notes. His thinking was so clear and well-supported precisely because his information was so well-ordered.
Locke’s story is a potent reminder. Our pursuit of the perfect digital tool can sometimes obscure the real goal: a trained mind and a disciplined hand. The power wasn’t in the parchment and ink; it was in the system. It was in the commitment to consistently process, tag, and connect ideas. Before we seek out the next feature-rich app, perhaps we should ask if we’ve first mastered the index.
Notes & further reading
A few pages I came back to while writing this: