Having just finished reading The Naked God (thus completeing the finest SF story ever written), I feel that this handbook is essential for clarifying a few of the finer points contained within the Nights Dawn Trilogy. It is wonderfully concise and as far as I can see there are no discrepencies between it and the novels. A number of my friends have expressed an interest in reading the Trilogy and my only recommendation to them was to borrow or buy a copy of this handbook with it. It really is that usefull for understanding some of the finer details of the society which Mr Hamilton has created. The only reason I have not given it 5 stars is because certain sections are a little dry and occasionaly repeated readings of these and other sections is essential to fully grasp the idea and concept it is referring to. But don't let this put you off this book in any way. On the whole, a worthy bookend to not just an excellent piece of science fiction but an outstanding masterpiece of modern fiction.