What was the purpose of the iudicium aquae in relation to corpses?

The iudicium aquae is an ancient judicial practice that involved submerging a body in water to determine whether it floated or sank. This practice was linked specifically to beliefs about vampirism in certain cultures. In these contexts, a floating body was often associated with the dead returning as a vampire, as it was thought that the supernatural nature of a vampire would prevent it from sinking. This reflects a societal fear and fascination with the undead, tying into the broader themes of the anthropology of the undead studied in the course.

While other purposes, such as determining the cause of death or performing burial rituals, do exist within different cultural and historical contexts, the unique association of the iudicium aquae specifically with floating bodies and the implications of vampirism are what make this answer correct in the context of the question posed.