The idea of mental illness is relatively recent.

In Biblical times, people who saw visions and heard voices were thought to be touched by supernatural forces. What sort of supernatural forces was decided by consensus, based on the 'touched" person's effects on the community. They were said to be under God's influence if their effects were good. If their effects were evil, they were said to be possessed by demons.

Even today, traditional societies tend to have similar views. If the "touched" person has a good heart and intentions, they are apprenticed to a healer or ceremonial leader. Otherwise, attempts are made to heal the person by banishing the evil spirit, or else the person is exiled or killed.

See also "The Origins of Consciousness in the Breakdown of the Bicameral Mind."