Neuromythology

In Greek mythology, when the common people, neither the overtly bad nor the overtly heroic, descended to the underworld they were deprived of the consolation of their memories of their previous lives by drinking the waters of the River Styx. 

This might be far-fetched, but one can't help but wonder whether this story represents some deep folk-remembering, some working of a collective unconscious trying to describe the effects of that most Stygian of neurological illnesses, 'Korsakov's Syndrome'.