His investigations into the usages and customs of his native Attica were embodied in an Atthis, in seventeen books, a history of Athens from the earliest times to 262 B.C. Considerable fragments are preserved in the lexicographers, scholiasts, Athenaeus, and elsewhere.
Philochorus in his Atthis (ap. Macrobius loc. cit.) further identified this divinity, at whose sacrifices men and women exchanged garments, with the moon.
Gilbert, who has investigated the sources from which Plutarch drew for his life of Theseus, believes that his chief authority was the Atthis of Ister, and that Ister mainly followed Philochorus (Philologus, xxxiii., 18 74, p. 46 sq.).
ATTHIS (an adjective meaning "Attic"), the name given to a monograph or special treatise on the religious and political history, antiquities and topography of Attica and Athens.
In the later story, Erichthonius (son of Hephaestus and Atthis or Athena herself) was handed over by Athena to the three daughters of Cecrops - Aglauros (or Agraulos), Hen and.