This paper examines various aspects of thought experiment that J. M. Coetzee conducts in Elizabeth Costello, focusing on its novelistic innovations. It also aims to clarify the implications of the novel’s narrative forms. Coetzee’s un/framing of Elizabeth Costello’s narrative as a series of lectures-as-fiction with its attendant unique variations provokes the readers to radically ruminate on the bases of human activities, including two of the notoriously blurring academic subjects, which are reason and sympathetic imagination. Elizabeth Costello’s thought experiment, while dismantling all kinds of internalized ideas and false consciousness by Kafkaesque mise en abyme, envisions how the modern novel can cope with the post-Einstein world and thereby creates the horizon of human possibilities sui generis embedded in non/human life.