Why a Knowledge Library Is Useful
No matter how thoroughly you read a book or article, over time you will forget most of the content. Re-reading a book is time-consuming and unnecessary, as this second reading usually offers no added value.
A much better option is to read through a short summary. There are numerous websites on the Internet that offer summaries of well-known literature, but these sites have two disadvantages. First, there may not be a (good) summary for new or unpopular books; second, the summary was written by someone else and not in your own words.
The only way out of this situation is to write your own summaries. This is time-consuming, but you will save the time in the long run, because you read each book only once. Of course, you can re-read particularly influential or beautiful books, but that is optional.
To sum up, the knowledge library is a collection of the summaries of all the books you have read. The summaries do not have to be written in whole sentences, short keywords will do.
Of course, you can also write notes on articles and videos, for example. In general, you read better and more profoundly.
How to Create a Knowledge Library
This approach is not a one-fits-all solution. Nobody reads or learns the same way, that's why knowledge collections are very individual. The following system is my own approach.
Make Notes While Reading
I have been reading my books only on my Kindle for quite some time now. While reading, I take handwritten notes on paper. It's important to write these key points in your own words so that you can still understand them later.
If I stumble across a quote that resonates with me, I highlight it with my Kindle. The quote is saved, and when I finish reading the book, I can export all the highlighted passages by sending them to my e-mail-address. You can also use the service “Readwise“ for better exporting.
Digitalizing the Notes
I usually type the notes at the end of the whole book or at the end of each chapter. As I type up my handwritten notes, I can improve any errors, rewrite them, and make other changes. I can check my summary for comprehensibility and indirectly review what I learned.
I save my book notes in a program called “Obsidian”. At the beginning of the note, I write down the author and title of the book; if it is an online article, I also copy the link of it.
Below that, chapter by chapter, follow my notes about the book or article. After that, I copy all the highlighted quotes from the book and paste them at the end of the document.
I usually link to notes of other books about a similar topic. If I want to find out more about a certain topic, it is easier for me this way.
If I particularly liked a book, I summarize it in a few sentences at the end. However, this only happens with books that are really good, since this summary naturally requires extra work.
If you want to learn more about how I organize my notes, I wrote a separate article about this topic.
Using the Knowledge Library
Depending on personal preference, you can either sort the books into categories or rely on linking them to each other.
I use both options by sorting the book notes into broad categories, such as science, biographies, or finance, and then linking them to each other.
Now, if I want to review my notes of a book, I open the corresponding document and can either read through the short summary at the end or go through the keywords chapter by chapter. In this way, I can refresh the knowledge of a book in a very short time.
 Tiago Forte's concept of “Progressive Summarization” explains how to summarize your notes more effectively to grasp the content even faster.