Chapter Three analyses the ‘theoretical’ connections that many physical-psychical scientists made between ‘physics and psychics’.It analyses general physical arguments against philosophical materialism and other ‘stumbling blocks’ to the idea of mind and spirit in the cosmos; vague analogies between physical and psychical effects; and more radical physical theories and explanations of telepathy and other psychical phenomena.The chapter highlights the extrordinary creativity of physical scientists in applying their concepts, ideas and theories to psychical puzzles.It also examines the criticism that many physicsts levelled against such psychical uses of physics and argues that while leading physical-psychical scientists accepted many of the problems with physical theories of largely non-physical phenomena, they never completely abandoned the idea that some kind of physical theory would ultimately help render psychical effects more intelligible.