2. Under the head of _time required_ it remains to give a synopsis of the latest and most reliable results of Egyptologists in regard to the Egyptian date of _Menes_, their first king, and of the building of the three great pyramids――these being the most important epochs of the earliest Egyptian antiquity. The standard historic authority (not, however, above suspicion) is Manetho, an Egyptian priest of Heliopolis, of the age of Ptolemy Philadelphus (reigned B. C. 284–246), who is supposed to have made up from the ancient records of his nation a list of thirty or thirty-one dynasties of Egyptian kings, beginning with Menes and ending with the conquests of Alexander the Great, giving the years of each king’s reign. Unfortunately it comes down in a somewhat fragmentary condition, as copied by Julius Africanus (died A. D. 232), who was himself in part copied by Eusebius (of the fourth century) and by Syncellus (flourished A. D. 780). Until recently it has been the current opinion of the best authorities (still held by many) that these dynasties were at some points _contemporary_ and not _successive_――some of them reigning in Upper Egypt, others in Middle or Lower Egypt, _at the same time_. This would raise the problems――How many and which were contemporary? How much is the entire period actually shortened by this contemporaneousness?――――Moreover it has been supposed also that on the same throne there has been at some points a joint occupancy of two or more kings――father and son perhaps, or of some rival claimants; so that the entire duration of a given dynasty may be less than the sum of the reigns of its enumerated kings.[20]――――The problem of whole duration being complicated by these elements of uncertainty, it has been the great aim of recent investigation to gather in all possible aid from the monuments and bring their testimony to bear upon the tables of Manetho. The results are variously estimated and the problem can not be regarded as yet fully settled. I place together the opinions of some of the best authorities: I. _For the date of Menes, reputed the first king._ B. C. Bunsen’s latest revised recension of Egyptian Chronology locates him[21] 3059 J. P. Thompson at least as far back as 3000 R. S. Poole (Smith’s Bible Dictionary, p. 682) 2717 Sir Gardner Wilkinson (see “Aids to Faith,” p. 294) 2690 Wm. Palmer (Smith’s Bible Dictionary, p. 687) 2224 The “Old Chronicle” (very valuable authority) 2220 Eratosthenes and ♦Apollodorus, original authorities, in no respect inferior to Manetho 2793 Other estimates from less reliable authorities carry him back yet further.