Einstein remarked that there was physics before Maxwell and physics after Maxwell, the difference being the introduction of modern field theory. So what difference did fields make and, more to the point, what are they? In this episode of the Sheldrake-Vernon Dialogues, Rupert Sheldrake and Mark Vernon explore how electromagnetic and gravitational, quantum and morphic fields shape modern science. They ask whether fields are a way that mechanistic understandings of nature have revived Aristotle’s notion of formal and final causes and look at the fact that fields aren’t energetic or material causes. They draw on ancient notions of soul to ask how fields can be part of an expansive notion of science, which has long drawn on entities that aren’t directly detectable to understand nature. Fields as realities in themselves are rarely discussed by scientists, the nature of fields hidden behind a fog of mathematics. But they fascinated figures like Faraday and Maxwell and might fascinate us again.