From pre-science to science; The origin of mathematics; The roots of physics and chemistry, and the urge to experiment; Are there limits to what science can know?; Understanding organisms: Goethe’s method; The quest for archetypal phenomena; Light, darkness and colour; The rediscovery of the elements; What is warmth?; The scale of nature; The working of the ethers in the physical; Sub-nature; What are atoms?; Natural science and spiritual science.