Cathryn Aison and Philip Glass's lovely abstract animation for Sesame Street (1979)

In 1979, Sesame Street animator Cathryn Aison created "Geometry of Circles," an abstract animation with original music by minimalist pioneer Philip Glass. It consists of four segments that were first aired as a complete piece. From the Muppet Wiki:

The shorts consist of the movement of six circles (each with a different color of the rainbow) that are formed by and split up into various geometric patterns. Glass's music underscores the animation in a style that closely resembles the "Dance" numbers and the North Star vignettes written during the same time period as his Einstein on the Beach opera.