6. LITERARY REMAINS; HISTORICAL; RELIGIOUS; EPISTOLARY; FICTITIOUS; SCIENTIFIC; EPIC; SATIRICAL AND JUDICIAL.--The Egyptian priests from the earliest times must have preserved the annals of their country, though obscured by myths and symbols. These annals, however, were destroyed by Cambyses (500 B.C.), who, during his invasion of the country, burned the temples where they were preserved, although they were soon rewritten, according to the testimony of Herodotus, who visited Egypt 450 B.C. In the third century B.C., Manetho, a priest and librarian of Heliopolis, wrote the succession of kings, and though the original work was lost, important fragments of it have been preserved by other writers. There seem to have been four periods in this history of ancient Egypt, marked by great changes in the social and political constitution of the country. In the first epoch, under the rule of the gods, demigods, and heroes, according to Manetho, it was probably colonized and ruled by the priests, in the name of the gods. The second period extends from Menes, the supposed founder of the monarchy, to the invasion of the Shepherd Kings, about 2000 B.C. In the third period, under this title, the Phoenicians probably ruled Egypt for three centuries, and it was one of these kings or Pharaohs of whom Joseph was the prime minister. In the fourth period, from 1180 to 350 B.C., the invaders were expelled and native rule restored, until the country was again conquered, first by the Persians, about 500 B.C., and again by the Greeks under Alexander, 350 B.C. From that time to the present no native ruler has sat on the throne of that country. After the conquest by Alexander the Great, who left it to the sway of the Ptolemies, it was successively conquered by the Romans, the Saracens, the Mamelukes, and the Turks. Since 1841 it has been governed by a viceroy under nominal allegiance to the Sultan of Turkey. In 1865 the title of khedive was substituted for that of viceroy. Early Egyptian chronology is in a great measure merely conjectural, and new information from the monuments only adds to the obscurity. The historical papyri are records of the kings or accounts of contemporary events. These, as well as the inscriptions on the monuments, generally in the form of panegyric, are inflated records of the successes of the heroes they celebrate, or explanations of the historical scenes painted or sculptured on the monuments.