Authors:

We might miss the sign or we may be unable to read the expression, but it is almost a contradiction in terms to say that a dog feels something but does not show it. What a dog feels, a dog shows, and, conversely, what a dog shows, a dog actually does feel.

Jeffrey Moussaieff Masson (1998). “Dogs Never Lie about Love: Reflections on the Emotional World of Dogs”, Broadway Books
We might miss the sign or we may be unable to read the expression, but it is almost a contradiction in terms to say that a dog feels something but does not show it. What a dog feels, a dog shows, and, conversely, what a