When Guildenstern is confronted with Hamlet's dubious invitation to ‘play upon this pipe’ (a recorder) a constrictive attitude is cruelly but artfully exposed. At another time and place Jung imagines an incredulous response to a creature so absurd that it should not exist (but does): the duck-billed platypus. Would the platypus, like Hamlet, have a complaint to make too? In this paper I use these examples, from very different kinds of literature, as touchstones to explore the ways in which the psychotherapeutic encounter can open up or, alternatively, shut down the way to ‘psychological understanding’, as Jung terms it. The paper addresses both the therapist's and patient's attitude to knowledge and in particular its relation to wonder which, I argue, can function in a way that can fruitfully open up the field for generative therapeutic change.