Keep notes on what you read. You can do this however you like. It doesn't need to be a big production or a complicated system. Just do something to emphasize the important points and passages.

You can do this in different ways depending on the format that you're consuming. You can highlight passages when reading on Kindle. You can dog-ear pages and transcribe notes when reading a print book.

But here's the real key: store your notes in a searchable format. There is no need to leave the task of reading comprehension solely up to your memory.

One way to imagine a book is like a knowledge tree with a few fundamental concepts forming the trunk and the details forming the branches. You can learn more and improve reading comprehension by “linking branches” and integrating your current book with other knowledge trees.

As soon as you finish a book, you can challenge yourself to summarize the entire text in just three sentences. This constraint is just a game, of course, but it forces me to consider what was really important about the book.

Some questions you can consider when summarizing a book include:

• What are the main ideas?
• If I implemented one idea from this book right now, which one would it be?
• How would I describe the book to a friend?

If you only read one book on a topic and use that as the basis for your beliefs for an entire category of life, well, how sound are those beliefs? How accurate and complete is your knowledge?

Reading a book takes effort, but too often, people use one book or one article as the basis for an entire belief system. This is even more true (and more difficult to overcome) when it comes to using our one, individual experience as the basis for our beliefs.

I'd like to finish by returning to an idea I mentioned near the beginning of this article: read great books twice. The philosopher Karl Popper explained the benefits nicely, “Anything worth reading is not only worth reading twice but worth reading again and again. If a book is worthwhile, then you will always be able to make new discoveries in it and find things in it that you didn’t notice before, even though you have read it many times.”

Additionally, revisiting great books is helpful because the problems you deal with change over time.