“My go at keeping a commonplace book using index cards - and how you can begin one too.” - The Museful Scribe

How to Keep a Commonplace Book Using Index Cards and the Dewey Decimal System

Imagine having a collection of your thoughts and inspirations organized in a way that allows you to dive into your writing without hesitation, knowing exactly where to find the ideas you need. It’s not about recording everything, but about capturing what resonates and sparks joy. I think of it as a personal library.

I glance at my old notebooks and journals. I’ve kept them for sentimental reasons, but also because I know they hold ideas and observations that could come in handy. However, the thought of retrieving those buried ideas is an overwhelming task. I've only taken the first step: sorting the journals into piles by decades and years.

Enter the Commonplace Book

What is a Commonplace Book?

In its simplest form, a commonplace book is a curated collection of quotes and favorite passages from books you’ve read. But when used as a writer, it can house everything from observations and insights to ideas for later use and inspiration. My focus for keeping a commonplace book has been to set it up in a way that compels me to revisit what I write down. That’s why I decided to use index cards rather than a notebook for my entries.

Why Index Cards and the Dewey Decimal System?

Each index card is a clear, accessible note. They are small and portable, making it easy to store, track, and revisit my ideas. I can also shuffle and reorder the cards. Each card is a standalone piece of fact or inspiration that fuels my writing.

The commonplace book is usually organized by category and topic, with an index to make it easy to find later. It should be simple enough, but I still manage to confuse myself with all the possibilities. That’s when I got excited about pairing my commonplace book with the Dewey Decimal System.

You might be wondering: why use a library classification system in a creative process? The Dewey Decimal System may seem rigid, but in reality, it offers freedom within structure. It’s an elegant system that divides knowledge into ten main categories and dozens of subcategories, allowing you to organize your ideas and inspirations in a way that makes sense to you.

Step-by-Step Guide: How to Use Index Cards and the Dewey Decimal System in Your Commonplace Book

1. Set Up Your Categories

The Dewey Decimal System divides human knowledge into ten categories, from philosophy and psychology to history and geography. These categories will be the building blocks of your commonplace book.

Here are the ten main categories to consider:

• 000 – General Works: Quotes, writing tips, and resources for creativity.

• 100 – Philosophy & Psychology: Insights into human nature, reflections on writing, or psychological concepts.

• 200 – Religion & Mythology: Symbolism, spiritual inspiration, or references to mythical creatures.

• 300 – Social Sciences: Ideas about human culture, society, or social interactions.

• 500 – Natural Sciences: Facts or inspiration drawn from nature—this is where you’ll catalog observations about animals, plants, and the environment.

• 600 – Technology: Ideas about the intersection of technology and creativity.

• 700 – Arts: Inspiration from visual arts, music, and performance.

• 800 – Literature: Literary techniques, quotes from your favorite authors, and notes on writing style.

• 900 – History & Geography: Ideas about places, time periods, and historical events that might inspire your writing.

2. Start Collecting Ideas

Begin by collecting any idea or piece of inspiration that resonates with you. Don’t worry about categorizing them yet; just capture the moment. For example, if you’re researching ornithology for a novel, you might jot down a fascinating fact about a bird.

Let’s say you learn that the Peregrine Falcon is the fastest bird of prey, reaching speeds of 240 mph in a dive. You would write that down, along with any thoughts or connections that arise.

3. Assign Dewey Numbers

Once you’ve gathered a few cards, it’s time to organize them using Dewey Decimal numbers. For example, the fact about the Peregrine Falcon would fall under 598.9 – Birds of Prey in the Dewey system. On your index card, write the following:

• Title: The Peregrine Falcon: Speed and Precision

• Dewey Number: 598.9 (Birds of Prey)

• Notes: “The Peregrine Falcon, capable of reaching 240 mph in a dive, is the ultimate symbol of speed and precision—perfect for the fast-paced protagonist in a thriller.”

This index card now becomes part of your personal library—a source of inspiration you can return to later. Over time, you’ll accumulate hundreds of cards like this, each capturing a unique idea or observation, all organized neatly and easily accessible.

4. Cross-Reference Ideas

As you collect more cards, you may notice that some ideas overlap. The beauty of the Dewey Decimal System is that you can cross-reference these cards. Maybe the symbolism of the falcon in mythology (found under 200.3 – Mythology) connects with your natural science observations (found under 500.11 – Ornithology). You can make notes on the cards to remind yourself of the connections.

For example:

• See also 200.3 for mythological symbolism of falcons.

• See also 500.11 for more birds of prey facts.

This cross-referencing allows you to draw connections between different realms of knowledge, sparking new ideas and inspiring your creative process.

5. Maintain Flexibility

While the Dewey Decimal System offers structure, your commonplace book should remain a place for free-flowing ideas. Don’t be afraid to break the rules or create new categories as your collection grows. The system is meant to guide you, not constrain you.

I write the Dewey main category number on colored envelopes, which I use as dividers for the index cards. That way, I can place the cards in the envelope if I need to take them with me instead of the whole box.

Using Your Commonplace Book for Creative Writing

By organizing your ideas in this way, you can easily access the information you need to develop your plots, characters, themes, and settings. The Dewey Decimal System turns your commonplace book into a dynamic, interactive tool that works with you throughout your creative process.

For example, when writing a novel, you might use a quote about freedom from 300.7 – Sociology to inspire a rebellious character. Or, if you’re creating a scene in a dense forest, you can pull out your notes about bird behavior and symbolism from 500.8 – Zoology, giving your setting depth and authenticity.

Final Thoughts:

By using index cards and the Dewey Decimal System in your commonplace book, you’ve created an accessible way to gather your ideas. The beauty of this method is that it allows for creative play while keeping the clutter at bay. When unruly thoughts are neatly tucked away, you can focus on what matters most: writing.

So go ahead—grab an index card, say goodbye to clutter and confusion, and soon you'll be holding your commonplace book: a living, breathing collection of ideas.