The notion 'animal spirits' was valid for many centuries, while modern science took a little more than two centuries to understand the phenomenon of nerve impulse transmission. The establishment of the scientific method and the development of new research techniques led several researchers at different times to unravel the molecular mechanisms involved in the transmission of nerve impulses, which took two and a half centuries to reach the current concept about the origin of action potential. Thus, the philosophical theory of 'animal spirits' led to the current concept of action potential, understood as a merely electrochemical phenomenon.
After conducting a bibliographical review on the works of various researchers at different times to explain the phenomenon of the transmission of nerve impulses, it is observed that since the eighteenth century, when modern science was born, scientific knowledge in the field of physiology had an accelerated development following the creation of new research techniques and the application of the scientific method.
