At the time when the Nile began to rise, or shortly before it, there appeared in Egypt from year to year a peculiar kind of heron, distinguished by two long feathers on the back of the head.[101] This was known to the Egyptians as Bennu. This bird, which announced or caused the fertilisation or new life of the land, could not but belong to the god of life. The whole race, or a select specimen, appears in special connection with Osiris, and the temple at Heliopolis. In the oldest portions of the Book of the Dead, which belong to the time of the Amenemha and Sesurtesen, we find, "I am that great Bennu of On" (Heliopolis); and the commentary adds, "Bennu is Osiris, viz., the Osiris in On."[102] The inscriptions say of the great Bennu that "it was self-begotten," that "it caused the divisions of time to arise."[103] This production of himself signifies the creative power of Osiris, and the origin of the seasons might well be attributed to the bird which regularly appeared announcing the return of the period of fertilization. With the cultus of the Bennu at Heliopolis is connected the story of the phoenix. Herodotus tells us that he was informed by the inhabitants of Heliopolis that a bird, which, if it resembled the pictures, was gold-coloured and red, and like an eagle in shape and size, came from Arabia to their city once in every 500 years, and buried the corpse of his father in myrrh in the sanctuary of the sun-god.[104] From later accounts we learn that the phoenix, on reaching the age of 500 years, prepared a funeral pile of spices, and burned himself upon it; then he recreated himself, and carried the remains of his old body to Heliopolis.[105] Tacitus says: "In the consulship of Paulus Fabius and Lucius Vitellius (_i.e._ in the year 34 A.D.) after a lapse of centuries, the phoenix appeared in Egypt. This bird, which was sacred to the sun, returned after an interval of 500 years, according to the most common accounts; according to others after an interval of 1461 years. The first phoenix appeared in the reign of Sesostris; the second under Amasis; the third in the time of the third Ptolemy; and as there was only a lapse of 250 years between this Ptolemy and the reign of Tiberius, some regarded the last phoenix as a spurious one."[106] Ælian remarks: "The Egyptians are not agreed when the 500 years are completed; and the priests were at variance whether the bird would appear then or later, and when he ought to come; but amid their dissensions the bird suddenly appeared at the right time."[107] Pliny informs us that the cycle of the great year was connected with the life of this bird, and with his return the stars came again into their old position.[108] Horapollo maintains that the phoenix was a symbol of the sun, and signified one who returned after a long time from a far country.[109] There is no doubt, therefore, that the alleged appearance of the phoenix signified to the Egyptians the close of an astronomical period.