In this article I am going to describe the system that I use to retain more information from the non-fiction books that I read. There seem to be two schools of thought about how to best retain the content of non-fiction books. The first approach is best described by the quote:

“I cannot remember the books I’ve read any more than the meals I have eaten; even so, they have made me.”- Ralph Waldo Emerson

By reading a lot, our brain retains what it finds interesting. Our prior beliefs are updated and specific ideas are enforced within us when we encounter the same or related concepts in different sources.

Some argue that proper retention can only be achieved by actively working through the material while reading it. This second approach commonly involves taking notes of the the major ideas of the book.

While I do experience surprise connection moments occasionally, there are two reasons why I invest time into taking good notes:

1. The first approach has an inherent survivorship bias. I do remember concepts from books and I am able to link them to other things. This always feels great. However, I don’t know about the missed opportunities of ideas that I have forgotten and that will never resurface.
2. Reading a non-fiction book is quite a significant time investment. For me it takes between a few days and several weeks. Taking at least basic notes seems to be a marginal additional cost for the certainty of improved retention and better ability to digest the book in the future.

I use a simple multi-pass approach that involves both analog and digital notes. I mostly read physical books, because I like to browse books on my shelf that I have read in the past. However, you can easily adapt this approach to ebooks.

1. Skim the table of contents, and try to understand the structure of the book.

2. Read the book and use a pencil to mark interesting sentences or paragraphs with a line in the margin (Fig. 1). In rare cases I use double lines to highlight especially noteworthy ideas. This helps later to quickly re-familiarize with the main concepts of a chapter without having to fully re-read it. I don’t typically write a lot of notes into the margin because there is usually not a lot of space available.

   

3. After finishing one or several chapters, I review the marked paragraphs and summarize the main points of each chapter on the empty space at the beginning or end of the chapter (Fig. 2). By writing the notes into the book I get two benefits. Firstly, there is a higher chance for these analog notes to still be accessible to me in a decade. Secondly, these notes might be interesting to friends that I lend the book to.

   

4. Once I finished the book, I transfer the chapter notes into a markdown file (in Joplin   ). While copying the notes I sometimes rework or modify them. I might also link to other digital notes that have a connection to the book.

5. Optional: If I want to share my notes with an audience I will write about the major learnings from the notes and bring them into context with concepts from other books/articles/experiences.

6. Optional: Most books will have some learnings that I want to periodically and actively recall. For those I create atomic Anki cards   which will prompt me to regularly review the concepts. I am trying to write good prompts   for these cards. This can be a mix of facts like “Where was Napoleon born?” or higher level concepts I don’t want to forget, e.g. “Give an example for an infinite game as defined by J. P. Carse”.

The most important rule for this note taking system is that I arbitrarily break the rules for certain books and skip some of these steps when I feel they are not worth the time. However, this system ensures that I do multiple passes of the content, that I have both durable analog and searchable digital notes, and that I am periodically prompted for the most interesting concepts.