I recently read Dianetics: the Evolution of a Science.  I'd read it before but, as with most of L. Ron Hubbard books, I find each time I read it I learn so much more.

What is really fascinating about this book, in my opinion, is the way Mr. Hubbard came to discover what he did about the mind.  He describes the path of discovery in this book -  the path of investigation he followed, what he looked into, what he discarded and why.

Not only does it give you a lot of insight into Scientology and Dianetics, but it is also a great lesson in how to do effective research and think out of the box.

Dianetics the Evolution of a Science can also be read online.