As, when something has caused motion in water or air, this moves another and, though the cause has ceased to operate, such motion propagates itself to a certain point, though there the prime mover is not present; just so it may well be that a movement and a consequent sense perception should reach sleeping souls from the objects from which Democritus represents and emanations as coming; that such movements, in whatever way they arrive, should be more perceptible at night, because when proceeding thus in the daytime they are more liable to dissolution (since at night the air is less disturbed, there being then less wind); and that they shall be perceived within the body owing to sleep, since persons are more sensitive even to slight internal movements when asleep than when awake.