(1) Sea Level
Reading A Dog's Purpose is easier than teaching a dog of any age tricks. The book's cover features the subtitle "A Novel for Humans," which means that you don't need to speak dog to understand it, nor do you need sophisticated knowledge of animal psychology. There are some difficult emotional moments, because in order for a dog to be reborn, he first has to die. But on a vocabulary basis, this is a book for humans of all reading levels.