For years I thought I had imagined this movie from my childhood. But there it is, on YouTube! This amazing piece of work fostered my love of classical mythology and anime.
Originally called "Metamorphoses" in Japan, "Winds of Change" was released in the United States in 1979. An animated retelling of stories from Roman poet Ovid, it is set to music by Joan Baez and Mick Jagger (with supplemental disco from Pattie Brooks), and narrated by Peter Ustinov.
I need offer no further recommendation.