When I am halfway finished working through a technical book I start longing to start the next one.

The beginnings of technical books are so much easier than the ends of them. There's so much promise in the introductions about what you'll be able to do if you can just cram all of this knowledge into your head.

However, as much as I always want to move on to the new, cool thing, there are huge benefits to picking up a book you've already read.

Gain a new perspective on skills you've been using.

When you're new to a concept you have to work hard to gain new knowledge.

Re-reading is easier.

When I take the time to do it I learn concepts I either misunderstood or missed completely. I find subtleties that only make sense now that I have been in the world working with the knowledge the book provided.

Take some of the pressure off of the first read.

On your first read through you don't know what points are fundamental principles, and which ones are tangential.

I used to drive myself crazy trying to master ever skill in every chapter. Knowing that an older, wiser, more experienced you is going to come back to this book eliminates the pressure to extract every morsel during the first reading.

Additionally, it's easier to understand a book when you know where it is heading.

Read books that are worth reading twice.

How precious is your time to you?

If you commit to reading a book twice you'll be more careful about the topics you read about, and the quality of materials you work with.

Do I re-read every single book I read? Absolutely not. However, I have gotten much more than I imagined out of re-reading books on fundamental topics, and I think it is an important tool in any programmer's toolbox.