To the demons and their relations to the gods and to men we therefore next come. Plutarch’s view is that they are essential mediators between the gods and men. Just as one who should remove the air from between the earth and moon would destroy the continuity of the universe, so those who deny that there is a race of demons break off all intercourse between gods and men.[931] On the other hand, the theory of demons solves many doubts and difficulties.[932] When and where this doctrine originated is uncertain, whether among the _magi_ about Zoroaster, or in Thrace with Orpheus, or in Egypt or Phrygia. Plutarch likens the gods to an equilateral, the demons to an isosceles, and human beings to a scalene triangle; and again compares the gods to sun and stars, the demons to the moon, and men to comets and meteors.[933] In the youth’s vision in the cave of Trophonius the moon appeared to belong to earthly demons, while those stars which have a regular motion were the demons of sages, and the wandering and falling stars the demons of men who have yielded to irrational passions.[934] [Sidenote: Demons in the moon: migration of the soul.] These suggestions that the moon and the air between earth and moon are the abode of the demons and this reminiscence of the Platonic doctrine of the soul and its migrations receive further confirmation in a discussion whether the moon is inhabited in the essay, _On the Face in the Moon_. A story is there told[935] of a man who visited islands five days’ sail west of Britain, where Saturn is imprisoned and where there are demons serving him. This man who acquired great skill in astrology during his stay there stated upon his return to Europe that every soul after leaving the human body wanders for a time between earth and moon, but finally reaches the latter planet, where the Elysian fields are located, and there becomes a demon.[936] The demons do not always remain in the moon, however, but may come to earth to care for oracles or be imprisoned in a human body again for some crime.[937] The man who repeats the stranger’s story leaves it to his hearers, however, to believe it or not. But the struggle upward of human souls to the estate of demons is again described in the essay on the demon of Socrates,[938] where it is explained that those souls which have succeeded in freeing themselves from all union with the flesh become guardian demons and help those of their fellows whom they can reach, just as men on shore wade out as far as they can into the waves to rescue those sea-tossed, ship-wrecked mariners who have succeeded in struggling almost to land. The soul is plunged into the body, the uncorrupted mind or demon remains without.[939] [Sidenote: Demons mortal: some evil.]