Why is the ninth month called September?
goddess of agriculture, mother of Persephone, from Greek Demeter; the second element generally given as mater (see mother); the first element possibly from da, Doric form of Greek ge "earth" (see Gaia), but Liddell & Scott find this "improbable." The Latin masc. proper name Demetrius means "son of Demeter."
The Greek and Roman goddess of grain, agriculture, and the harvest. The story of Demeter and her daughter, Persephone, explains the cycle of the seasons. When Persephone was carried off to the underworld by Hades, Demeter was so forlorn that she did not tend the crops, and the first winter came to the Earth. Eventually Zeus allowed Persephone to rejoin her mother for two-thirds of every year, and thus the cycle of the seasons began.