 Each side of Fechner’s personality bore its characteristic fruit. The product of his positivist side was his early scientific work on the psychology of perception, and his massive two volume work Elemente der Psychophysik (1860), which attempts to describe in precise laws the relationship between the psychic and physical. Because it stressed the dependence of the mental on its physical expression and embodiment, Fechner’s philosophy of mind has been described as a form of materialism. The product of his metaphysical side is his so-called “panpsychism”, the the doctrine that the cosmos is psychic, that it is an embodiment of the psychic (for a more precise definition of this term,  see below, section 4).  Fechner put forward this doctrine in his two most famous works: Nanna oder über das Seelenleben der Pflanzen (1848a) and Zend-Avesta oder über die Dinge des Himmels und des Jenseits (1851). 