Reading a great book (specifically nonfiction) is to acquire, within a matter of hours, the insights and knowledge that the author spent months, years, and sometimes decades developing. Books are therefore knowledge multipliers, shortcuts to years of research and thinking, and the more books you read, the more hard-won knowledge you accumulate in a fraction of the time.
Reading is therefore your most powerful intellectual tool. This means that you had better get it right, otherwise you are squandering your best opportunity to enhance your intellect and understanding.
We all read for different reasons, sometimes simply for entertainment or to extract some quick information, but reading for true self-improvement comes from intentional, analytical reading. The question is, how do you optimize your reading habits for maximum intellectual development?