Simplify the following text for a Grade 15 native English-speaking person.
Original: During the late 1890s Freud , who never abandoned his belief in the sexual etiology of neuroses , began to emphasize fantasies built around the Oedipus complex as the primary cause of hysteria and other neurotic symptoms .
Simplified: During the late 1890s Freud , who never abandoned his belief in the sexual cause of neuroses , began to emphasize fantasies built around the Oedipus complex as the primary cause of hysteria and other neurotic symptoms .