> once I finish a book I immediately replace it for the next one on my to-read list. This right here is your problem. The way to really learn a book is to rea

> once I finish a book I immediately replace it for the next one on my to-read list. This right here is your problem. The way to really learn a book is to read it and then solve a lot of problems out of it, referring to it often. If it's a programming book (that's ideal), write programs that do what you read about. If it's a textbook there should be a lot of exercises for you to do. If there aren't any exercises you'll have to make up your own. That's a slow process, but it's still a more reliable route to deep understanding than reading superficially and never getting there. That said, you remember more than you think you do. You may not recall everything you read, but a lot of that information is in your head somewhere, ready to act as foundation and building material if you ever visit the material again. You'd be amazed how much more you can get out of a book just by skimming it a second time, once you've got the big ideas.