Of the so-called "Prehistoric Age" it is obvious that no strict definition can be given. It comprises in a general way that vague period prior to all written records, dim memories of which--popular myths, folklore, demi-gods[109], eponymous heroes[110], traditions of real events[111]--lingered on far into historic times, and supplied ready to hand the copious materials afterwards worked up by the early poets, founders of new religions, and later legislators. That letters themselves, although not brought into general use, had already been invented, is evident from the mere fact that all memory of their introduction beyond the vaguest traditions had died out before the dawn of history. The works of man, while in themselves necessarily continuous, stretched back to such an inconceivably remote past, that even the great landmarks in the evolution of human progress had long been forgotten by later generations. And so it was everywhere, in the New World as in the Old, amongst Eastern as amongst Western Peoples. In the Chinese records the "Age of the Five Emperors"--five, though nine are named--answers somewhat to our prehistoric epoch. It had its eponymous hero, Fu Hi, reputed founder of the empire, who invented nets and snares for fishing and hunting, and taught his people how to rear domestic animals. To him also is ascribed the institution of marriage, and in his time Tsong Chi is supposed to have invented the Chinese characters, symbols, not of sounds, but of objects and ideas. Then came other benevolent rulers, who taught the people agriculture, established markets for the sale of farm produce, discovered the medicinal properties of plants, wrote treatises on diseases and their remedies, studied astrology and astronomy, and appointed "the Five Observers of the heavenly bodies." But this epoch had been preceded by the "Age of the Three [six] Rulers," when people lived in caves, ate wild fruits and uncooked food, drank the blood of animals and wore the skins of wild beasts (our Old Stone Age). Later they grew less rude, learned to obtain fire by friction, and built themselves habitations of wood or foliage (our Early Neolithic Age). Thus is everywhere revealed the background of sheer savagery, which lies behind all human culture, while the "Golden Age" of the poets fades with the "Hesperides" and Plato's "Atlantis" into the region of the fabulous.