Most likely no one is going to like this post. My father was a physicist and he had a large library of books. Growing up all of these books were over my head but I tried reading all of them. The more difficult the book the more determined I became to read and understand the content. I found this to be mind expanding. I began a life long quest to read the most difficult books and texts I could find. It sometimes takes several passes. Some things didn't make sense until years later. I recommend reading outside your comfort zone and above your comprehension. The book doesn't expand your mind it's the reading process and thinking about the reading that forces the mind to expand. I have done this for 50 years and I still do it every day It's not one book but the sum total of books that expand your mind. Read with curiosity and an unquenchable thirst for knowledge. A man who reads one book lives once life while a man who reads a thousand books life experiences thousands of lives. I hope these word aren't wasted. I thought my fathers library was the library of Alexandria and it was until I got a library card.