It seems like a stupid question – obviously, we read in order to process written material until we understand it.
People have different motivations for reading. While fiction books are a source of entertainment non-fiction/reference material is a source of learning and discovering new ideas.
In the context of non-fiction, we normally read to learn something. We want to know more about what made Steve Jobs Steve Jobs, we want to learn more about thinking, creativity, health, business etc.
Yet most of us only read books once. Worse, we normally read them in fits and starts, easily forgetting the salient points from the chapters that came before. It's almost like the goal isn't to understand and learn from the content, but simply to finish the book.
I find myself in this trap repeatedly; believing that once I've finished reading the book I'm done – I've learnt all the lessons and I'm ready to move on. During conversation, "Yeah, I've read that book.", I remark, as if I remember anything more than a vague, hazy recollection of the most engaging story from it.
The truth is, I sometimes forget what's on my daily to-do list – there's no freaking way I'm remembering the experience, advice and lessons of the author's many months of hard work for more than a few days afterwards.
In most of the best non-fiction books I've read, there's at least one or two very good points, stories or lessons that I'd like to try and internalise myself, or at least have to mind when a future situation fits. For me, this is growing – it's taking the lessons and knowledge of others and actively trying to use them to better yourself. It's having an altered mindset due to being able to factor in things you never knew about before.
It's no good if you read a great book once and then forget most of the salient points, lessons and advice. We don't treat other subjects this way, instead we study them. We spend time with the material (more time than is necessary to read just once) because we know that without studying and thinking about it, we can't truly learn from it.
Books are amazing things. The right book is an opportunity to grow/alter your mindset, your thought process and your beliefs, but only if you allow it to. Simply aiming to get through it with no intention of studying and thinking about it doesn't work – you eventually forget it.
Reading is not the goal. Learning and growing is the goal, and that often necessitates not just reading, but studying, thinking and making an effort to let it stay with you.
So, what can you do? Here are some things that have worked for me:
Read the book more than once. Like a good movie (which typically has way less detail), you miss so much the first time. The second, third and nth time reading the same book is an opportunity to recall the things you remember and focus way more on the things you missed (or didn't think about) the previous times. I've occasionally re-read a chapter directly after finishing it too – sort of like double-entry reading.
Recite the book and its main points to someone who hasn't read it. I've always found teaching to be learning in disguise. Trying to explain the book to someone who hasn't read it will force you to think about the meaning of what you read, and it'll quickly expose things you didn't really understand.
Most importantly, study it. Contemplate with yourself how its main points apply to your life and your goals. Prompt yourself days and weeks afterwards to remember why it was useful, what the salient points were and how you intend to incorporate it.
In the end, reading is just a tool. The value is in the learning and how you let that change your attitude and mindset.