“Dogs can never speak the language of humans, and humans can never speak the language of dogs. But many dogs can understand almost every word humans say, while humans seldom learn to recognize more than half a dozen barks, if that. And barks are only a small part of the dog language. A wagging tail can mean so many things. Humans know that it means a dog is pleased, but not what a dog is saying about his pleasedness. (Really, it is very clever of humans to understand a wagging tail at all, as they have no tails of their own.) Then there are the snufflings and sniffings, the pricking of ears—all meaning different things. And many, many words are expressed by a dog’s eyes.”