Take a story's temperature by studying its tone. Is it hopeful? Cynical? Snarky? Playful?
This book lets actions and reactions speak for themselves. Unlike pure fantasy books like The Lion, the Witch, and the Wardrobe, for example, where fantasylands are described in loving and exquisite detail, in this book Terabithia exists only in the characters' minds. We readers can't see Terabithia except as Jess and Leslie perceive it – we have to imagine it along with them. Paterson's understated tone enables us to take part in that transformation along with Jess and Leslie, and to follow along as they create a fantasyland where other people might just see an ordinary patch of forest. Paterson's use of understatement is particularly poignant when bad things happen. There's no need to go into detail about why the bad things are so awful: we, and Jess, already know.