Modern science can speak with authority regarding only a tiniest fraction of the earth's interior. We have, quite literally, scratched just the surface of our planet. Can we truly know what lies beneath our feet, in the unimaginably deep depths of the earth? Can the phenomenon of spiritual investigation add to this question? In this comprehensive volume, with notes and an introduction, Rudolf Steiner's utterances on this theme have been brought together for the first time under one cover. His unique overview gives a picture of the nine layers of the earth as they become visible via the research of the spiritual scientist. The layers range from the familiar 'mineral' on which we live, to the innermost core which Steiner connects to human and animal powers of reproduction. In between are layers such as the 'Mirror Earth', which represents qualities of extreme evil, and the 'Fire Earth', which is connected to natural catastrophes. The information Steiner conveys is never abstract or theoretical, but intimately related to the human being. The Fire Earth, for example, is acutely affected by people's will. When the human will is chaotic and untutored, says Steiner, it acts magnetically on this layer and disrupts it, leading to volcanic eruptions. He also describes other natural catastrophes - such as extreme weather and earthquakes - in connection to the interior of the earth and karma.