This book is designed as the study guidebook for a 13-session course that examines some 60 lectures by Rudolf Steiner that discussed the future of the physical and etheric bodies. The picture that unfolds reveals our relationship to an Ahrimanic double that began in Lemurian times but must conclude by the end of the 6th Post-Atlantean Cultural Age (roughly by about 6000 AD). The etheric body will be increasingly loosening with the physical body causing it to wither more and more. The Ahrimanic double will seek to replace withered body parts with mechanical ones. This activity is already underway.