I have a copy of this on a shelf by my desk. From Chapter 1 - "Whatever else you do, keep using the computer. If you have the question “what does it do if I tell it such and such?” then the answer is easy: type it in and see. Whenever the manual tells you to type something in, always ask yourself, “what could I type instead?“, and try out your replies. The more of your own programs you write, the better you will understand the computer."