Mahāvastu that several of the Buddha's relatives had premonitory dreams preceding this. Some dreams are also seen to transcend time: the Buddha-to-be has certain dreams that are the same as those of previous Buddhas, the Lalitavistara states. In Buddhist literature, dreams often function as a "signpost" motif to mark certain stages in the life of the main character. Buddhist views about dreams are expressed in the Pāli Commentaries and the Milinda Pañhā. Other In Chinese history, people wrote of two vital aspects of the soul of which one is freed from the body during slumber to journey in a dream realm, while the other remained in the body. This belief and dream interpretation had been questioned since early times, such as by the philosopher Wang Chong (). The Babylonians and Assyrians divided dreams into "good," which were sent by the gods, and "bad," sent by demons. A surviving collection of dream omens entitled Iškar Zaqīqu records various dream scenarios as well as prognostications of what will happen to the person who experiences each dream, apparently based on previous cases. Some list different possible outcomes, based on occasions in which people experienced similar dreams with different results. The Greeks shared their beliefs with the Egyptians on how to interpret good and bad dreams, and the idea of incubating dreams. Morpheus, the Greek god of dreams, also sent warnings and prophecies to those who slept at shrines and temples. The earliest Greek beliefs about dreams were that their gods physically visited the dreamers, where they entered through a keyhole, exiting the same way after the divine message was given. Antiphon wrote the first known Greek book on dreams in the 5th century BCE. In that century, other cultures influenced Greeks to develop the belief that souls left the sleeping body. Hippocrates () had a simple dream theory: during the day, the soul receives images; during the night, it produces images. Greek philosopher Aristotle (384–322 BCE) believed dreams caused physiological activity. He thought dreams could analyze illness and predict diseases. Marcus Tullius Cicero, for his part, believed that all dreams are produced by thoughts and conversations a dreamer had during the preceding days. Cicero's Somnium Scipionis described a lengthy dream vision, which in turn was commented on by Macrobius in his Commentarii in Somnium Scipionis. Herodotus in his The Histories, writes "The visions that occur to us in dreams are, more often than