[108d] and encouragement, and in addition to the gods you mentioned I must call upon all the rest and especially upon
Mnemosyne.1 For practically all the most important part of our speech depends upon this goddess; for if I can sufficiently remember and report the tale once told by the priests and brought hither by Solon, I am wellnigh convinced that I shall appear to the present audience to have fulfilled my task adequately. This, then, I must at once proceed to do, and procrastinate no longer.
...
[109e]
to their descendants, concerning the mighty deeds and the laws of their predecessors they had no knowledge, save for some invariably obscure reports
Compare to:
https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Manetho/Introduction*.html
"Heliopolitan priest, Manetho (to quote from Laqueur, Pauly-Wissowa-Kroll, R.‑E. XIV., 1061) "was, without doubt, acquainted with p. xii the sacred tree in the great Hall of
Hêliopolis, — the tree on which the goddess
Seshat, the Lady of Letters, the Mistress of the Library,
wrote down with her own hand the names and deeds of the rulers.11 He did nothing more than communicate to the Greek world what the goddess had noted down.12 But he did so with a full sense of the superiority which relied on the sacred records of the Egyptians in opposition to Herodotus whom he was contradicting" (Fr. 43, § 73: Fr. 88). His native town, Sebennytus, was visited as a place of learning by Solon when Ethêmôn was a priest in residence there (see Proclus in Plat. Tim. I.101, 22, Diehl); and the Greek culture of the place must have been a formative influence upon Manetho at an early age. "