Perception of the unseen

In the Muqaddima, Ibn Khaldun classifies the ways people perceive the unseen, and explains them by saying that the veil of the body is momentarily lifted from the soul. ²

He lists soothsaying; looking into transparent things such as mirrors and basins of water; looking into the hearts, livers, and bones of animals; augury from birds and beasts; and casting pebbles and grains. He mentions the speech of madmen, and the speech of a sleeper or of a dead person at the moment of his first death or sleep. He mentions the perceptions of the practitioners of discipline among the Sufis, as a kind of charisma. ²

Ibn Khaldun holds that the soul is spiritual, and that the senses veil it by drawing it outward. When it is immersed in the inward, the veil of the body is lifted for a moment. This may be due to a general property in human beings, as in sleep; or to some people, as in soothsaying; or through discipline among the people of unveiling. ²

He says that the perception of madmen is mixed with falsehood, because of the corruption of their temperaments or because of the intrusion of satanic souls. ²

This is Ibn Khaldun's explanation alone. The views of others need a further source.