The temple of Ra was said to have been, to a special degree, a depository for royal records, and Herodotus states that the priests of Heliopolis were the best informed in matters of history of all the Egyptians. Heliopolis flourished as a seat of learning during the Greek period; the schools of philosophy and astronomy are claimed to have been frequented by Orpheus, Homer, Pythagoras, Plato, Solon, and other Greek philosophers. Ichonuphys was lecturing there in 308 BC, and the Greek mathematician Eudoxus, who was one of his pupils, learned from him the true length of the year and month, upon which he formed his octaeterid, or period of 8 years or 99 months. Ptolemy II had Manetho, the chief priest of Heliopolis, collect his history of the ancient kings of Egypt from its archives. The later Ptolemies probably took little interest in their "father" Ra, and Alexandria had eclipsed the learning of Heliopolis; thus with the withdrawal of royal favour Heliopolis quickly dwindled, and the students of native lore deserted it for other temples supported by a wealthy population of pious citizens. By the first century BC, in fact, Strabo found the temples deserted, and the town itself almost uninhabited, although priests were still present.