Knowledge Concepts
A commonplace book is a personal collection of quotes, ideas, passages, and observations gathered from reading and experience — organized for retrieval and creative use. It's the original external memory and idea repository, practiced by writers for centuries.
A commonplace book is a personal anthology of quotations, ideas, observations, and passages drawn from reading and experience — gathered in one place and organized for retrieval and use. Writers kept commonplace books to collect the raw material of thought: striking sentences, useful arguments, vivid examples, and memorable phrases encountered in reading. The commonplace book is the oldest form of personal knowledge management — a reading notebook organized for creative and intellectual use rather than linear reading.
Montaigne, Francis Bacon, Thomas Jefferson, and John Locke all kept commonplace books. So do many contemporary writers.
Ancient origins: The practice of collecting notable passages has roots in classical antiquity. Roman rhetoricians maintained collections of exempla (examples) and sententiae (wise sayings) for use in oratory. Quintilian and Cicero both advocated collecting material from reading as preparation for writing and argument.
Renaissance formalization: Erasmus's De Copia (1512) systematized commonplacing as a humanist educational technique: students were instructed to keep notebooks organized by topic or theme, copying out passages from their reading under headings like "Virtue," "Courage," or "Fortune." This practice spread through European universities for centuries.
John Locke's method (1685): John Locke devised a particularly systematic approach — an index by first letter and vowel of topics — published as A New Method of Making Common-Place-Books (1706). Locke's method allowed rapid retrieval from a growing notebook.
Notable practitioners:
A commonplace book captures content across four broad types:
Quotations: Passages worth preserving from books, articles, speeches, or conversations. The commonplace book is not about summarizing — it's about capturing the exact words that struck you. The author's specific phrasing often matters; paraphrasing loses it.
Ideas and observations: Your own thoughts, provoked by reading or experience. Not quotations from others, but the idea you had when you put the book down. The commonplace book is where thinking happens between reading sessions.
Examples and anecdotes: Specific stories, cases, and examples that illustrate abstract principles. Writers often struggle to remember examples when writing; a commonplace book indexed by theme gives you a searchable bank of concrete illustrations.
Connections: Notes linking one entry to another: "This reminds me of X" or "Compare to the Feynman observation on page 43." Connections are often the most valuable entries — they're where synthesis begins.
A journalist is writing a book on attention and distraction. Over three years of research, they maintain a digital commonplace book:
Organization: Topics organized alphabetically (Attention, Boredom, Creativity, Distraction, Focus, Memory...).
Entry under "Attention":
"Attention is the rarest and purest form of generosity." — Simone Weil, Waiting for God (1951) [personal note: use for chapter opener? pairs with the Attention Economics section]
Entry under "Distraction":
"The successful conduct of life depends upon the ability to postpone... attention." — William James, Principles of Psychology (1890) [note: James saw this as a feature, not a bug — selective inattention as cognitive resource conservation]
Entry under "Focus":
Example: Cal Newport describes a postdoc who writes 4 high-quality papers per year by working in uninterrupted 4-hour blocks, no email during work hours. [Deep Work, p.28] [note: concrete example for the productivity chapter; pair with the surgeon/CEO contrast]
When writing: The journalist searches "distraction" — finds 40 entries: quotations, examples, their own observations. The raw material for a chapter is already organized. Writing draws on the commonplace book rather than their (unreliable) memory of three years of reading.
| System | What it captures | Organization | Primary use |
|---|---|---|---|
| Commonplace book | Quotes, ideas, examples, connections | By theme/topic | Writing and creative use |
| Zettelkasten | Atomic ideas, linked notes | By concept links | Idea emergence and connection |
| Second brain (CODE/PARA) | Anything that resonates | By project/area | Project support and expression |
| Research database | Sources with citations | By source or topic | Academic reference |
| Diary / journal | Personal reflection, daily events | Chronological | Personal reflection |
The commonplace book is most similar to the second brain — but with a narrower focus on what's worth capturing verbatim (the exact quote, the specific example), and an orientation toward writing and creative output rather than project management.
The practice translates directly to digital tools:
Step 1 — Choose a capture method: The most important step is making capture frictionless. Options:
Step 2 — Capture verbatim and source it: The discipline: for quotations, copy the exact words. Include: author, source, page number (or URL for online sources). You'll need to find the quotation again; you need to know where it came from.
Step 3 — Add your own note: After every entry: add 1-2 sentences of your own thought. "This applies to X," "Compare to Y," "Use for Z," "Question: does this hold when..." The entry alone is the author's thought; the note is yours. The combination is more valuable than either alone.
Step 4 — Organize by theme: Whether alphabetical (Locke's method), by tags, or by a folder structure — organize by the themes that matter for your work, not by source. When writing about Focus, you want all your Focus entries together, regardless of whether they came from neuroscience papers, novels, or philosophical texts.
Step 5 — Review before writing: Before any substantial writing, spend 15-20 minutes reviewing relevant sections of the commonplace book. The raw material is there; the writing session starts from abundance rather than a blank page.
"It's just quote collecting." Quote collecting without notes is a list of other people's words. The commonplace book's value is in your own thinking provoked by those quotes — the annotations, the connections, the applications you identify. The quotes are prompts; your notes are the product.
"I need to read everything before I can start." Start now with whatever you're reading. A commonplace book begun today with 10 entries is more useful than one planned for later with hundreds of entries never written. The value compounds from the start.
"It should be organized perfectly before I use it." The commonplace book is a working document, not an archive. Organization should serve retrieval — enough to find things when writing — not be comprehensive enough to impress an archivist. An imperfect system you use beats a perfect system you maintain.
Zettelkasten: The more systematic note-linking alternative — each note is atomic and explicitly linked to others. Higher overhead than a commonplace book but produces more emergent connections.
Annotated bibliography: The academic parallel — documenting and evaluating sources rather than collecting their best passages.
Second brain: The contemporary PKM framework that includes commonplace book functions within a broader project-support system.
Should I keep a commonplace book by hand or digitally? Both work. Physical notebooks are more personal and some writers find handwriting improves retention; digital is more searchable and accessible across devices. Ryan Holiday keeps a physical card index; Maria Popova uses a digital system. The question is: what will you actually maintain? A physical notebook you'll abandon is worse than a digital system you'll use.
What if I don't read much? Commonplace books work with any content: podcasts (transcribe key ideas), conversations (capture immediately after), your own thinking (capture when it occurs), films and lectures. The source material is everything you encounter, not just books.
How often should I review my commonplace book? Review the relevant sections before writing — don't review the whole thing weekly for its own sake. The commonplace book's value is retrieval at the point of use, not periodic review of everything. That said, some practitioners do a monthly scan of recent entries to find connections they didn't notice when writing them.
The commonplace book is the writer's companion to reading — the place where encountered ideas are preserved and processed before they serve creative work. The modern knowledge environment makes the practice more valuable than ever: we encounter more potentially useful content than any biological memory can retain. A digital commonplace book organized by theme, populated with verbatim quotes and your own connecting notes, provides what our memory can't: permanent, searchable access to the best thinking you've encountered.
More WebSnips articles that pair well with this topic.
What is a commonplace book? A clear explanation of the centuries-old knowledge collection practice, famous examples, and how to build a modern digital version for writers and researchers.
Intermediate packets are small, discrete, reusable units of work — an outline, a research summary, a slide deck draft, a set of notes — that can be saved and reused across future projects rather than starting from scratch each time.
A bullet journal (BuJo) is an analog organization system created by Ryder Carroll using a dot-grid notebook: rapid logging with bullet symbols, collections (logs, trackers, lists), and migration (intentional task review). It combines daily planner, to-do list, diary, and habit tracker in one notebook.