Once ‘animal spirits’ were fluid beasts, distilled from blood, that roamed our nervous system and rummaged the pores of our brain. The patterns of their flow carried the contents of our thoughts and were the going explanation for vision, memory, imagination, belief, passion and desire. When animal spirits misbehaved or became polluted they could make us ill, in both body and soul. For most of this millennium Westerners firmly believed in these lively and impish carriers of our identity and they only disappeared after the nervous system was found to be electrical in nature. This week, philosopher John Sutton sets a few animal spirits free to explore the mind in history. This radio program was carried out with Natasha Mitchell.