The new edition of Jacob Böhmes writings and letters begins with his short but, from a philosophical point of view, extremely demanding Gründlichen Bericht vom irdischen und himmlischen Mysterio (Basic Account of the Earthly and Heavenly Mystery), also known as Mysterium Pansophicum, which was only preserved in copies. In it, Böhme developed the main feature of his cosmology of Gods self-generation up to the creation of the world and man in nine texts, each of which is based on the previous one. Of pivotal significance is the concept of the un-ground, to which Böhme gave a new interpretation and which like no other is directly linked to his name and his doctrine. The first sentence, 'Der Ungrund ist ein ewig Nichts' (The un-ground is an eternal nothingness), is the key element of this work.