These theories made it easier than the first one had done to establish a firm connection between ethical beliefs concerning future destiny and physical theories about the constitution of the universe and the nature of man. The soul is never conceived by these theologians as purely spiritual or immaterial, but when it abandons itself to the passions it becomes gross; its substance grows more corporeal; and then it is too heavy to rise to the stars and gain the spheres of light.[403] Its mere density will compel it to float in our mephitic atmosphere until it has been purified and consequently lightened. Thus the door is opened to all doctrines concerning punishment beyond the grave. We shall show in another lecture[404] how the soul was to be purified by passing through the elements which moved in sublunary space—air, water and fire. But, side by side with physical ideas, mythological beliefs always retained their sway. According to the common creed, the air was peopled with troops of perverse and subtle demons. They were, it was thought, the guilty souls whose faults condemned them to wander perpetually near the surface of the earth. They took pleasure in inflicting a thousand tortures on their fellow souls, when these, by their impiety, were left defenceless against them. But succouring powers protected the good against these perverse spirits. Thus the atmosphere became the scene of an unceasing struggle between demons of every kind, a struggle in which the salvation of the soul was at stake. The dangers to which the soul was exposed did not always end when, after having crossed the most dangerous zone of the air, it reached the moon.[405] Those who believed that souls must pass through the planetary spheres conceived these as pierced by a gate guarded by a commander (ἄρχων) or, as they were also called, by toll gatherers (τελώνια). The mystics claimed to supply their initiates with the passwords which caused the incorruptible keepers to yield. They taught prayers or incantations which rendered hostile powers propitious; by “seals” and unctions they made their followers immune against the blows of such enemies. These instructions, which were previously given to the dead in order to facilitate their descent to the nether world (p. 148), now served to make the ascent to heaven easy. In this matter the magicians emulated the priests, even claiming to show to their clients the way leading to heaven during life. The papyrus of Paris, wrongly called the “Mithraic Liturgy,”[406] affords the most characteristic example of this superstitious literature.