The question, »Do we know what a body is capable of?« is central to Spinoza's Ethics, because it brings into view the physical basis of mental activity. He repeatedly asks his philosophical opponents how the »somnambulistic creativity« of Nature might be understood. It produces complex structures without having these presented in advance mentally. This volume goes into the issue, addressing three key questions: How does the somnambulistic power of nature come up in religious discourses? In which body performances does it expresses itself? And what view of thought is generated by such body thought?