In the very first chapter (the Introduction) he says right away that he's manic depressive and suffers from delusions. He also goes on to state that there may be delusions stated in this book!
Here's the quote:
The ideas in this book - in particular, the recommended cure for a wide range of illnesses and diseases which I explain in Chapters 5 (Cure) - may therefore be delusional. Certainly, my psychiatrist, my brother who is a doctor, my family and my close friends think that my theories in Chapter 4 (Common Cuse) and my recommended cure in Chapter 5 (Cure) are delusional. I have not discussed with them the other parts of this book.
So, grain of salt people. :) But I'm sure it's interesting.