A good book outlining the history and philosophy of Osteopathic medicine is "The Difference a D.O. Makes" by Bob E. Jones.
The only place I know of to get it is from this website: <a href="http://www.okosteo.org/book.html" target="_blank">http://www.okosteo.org/book.html</a> --Mr Jones used to be the Director of the Oklahoma Osteopathic Association, so that is why you can get it from them.
Around here, I've heard it referred to as the D.O. Bible.