I absolutely adore the music of Philip Glass, who is often considered the greatest composer alive, and I love all things Sesame Street — who doesn’t? In 1979, the makers of Sesame Street commissioned Philip Glass to compose music for a series of four unnumbered animation pieces titled Geometry of Circles, designed as a primer for visual thinking — something at the core of both Sesame Street itself and Jim Henson’s original vision that predated his creation of The Muppets. The combination, beautiful and eloquent in a multisensory way, feeds into my obsession with synesthesia and various visualizations of music.

Here is the final piece of the series, from episode 2415, the only high-quality version known to exist online:

Geometry of Circles is available on the excellent 2009 DVD, Sesame Street: 40 Years of Sunny Days — a collection of nearly five hours of the best Sesame Street segments from all 40 seasons, including over 50 minutes of rare, never-before-seen backstage footage, interviews and vintage episodes not available online. There are really no words to describe what a treat and treasure this is.

via Image Oscillite

UPDATE: The film was apparently designed, animated, and produced by Cathy Aison, at the time an independent filmmaker who proposed a detailed storyboard to CTW producer Edith Zarnow in 1978. Once the script was approved, Sesame Street contracted her to make the film and she reached out to Philip Glass to record the music based on the storyboarded images. Glass licensed her the music for 20 years, a license that expired in 1999. Says Aison, “Although Sesame Street paid for and owned the rights to the film they were only indirectly the true author.” Aison is currently an art director at Random House’s Vintage Books division.