Recently a friend of mine posted a neat quote by Wittgenstein:
One can imagine an animal angry, fearful, sad, joyful, startled. But hopeful? And why not? A dog believes his master is at the door. But can he also believe that his master will come the day after tomorrow? —And what can he not do here? —How do I do it? — What answer am I supposed to give to this?Can only those hope who can talk? Only those who have mastered the use of language? That is to say, the manifestations of hope are modifications of this complicated form of life. (Ludwig Wittgenstein, “Philosophy of Psychology — a Fragment,” i.)