The author claims to have been lying in bed in the early hours of one morning in 1977, when an incredible thing happened - his 'metaphysical self' split from his physical self (which stayed in bed and wrote down what was happening) and went walking off to have an astounding metaphysical journey.
It is that journey which is related in this book. Depending on who you are, what you believe/don't believe, this book is either an imaginative rambling account of someone making it all up, or, it actually seems to make sense to you, perhaps you've had experiences like the author, or just really really want to!
It's up to you to decide.