Geometry of Circles (Philip Glass) (1979)

Inspired by some RecLeaguers recently posting the incredibly hypnotic Mr Rogers Goes to the Crayon Factory, it made me think of another piece of TV ephemera that restructured my brain as a child. Soothing and terrifying all at once. Cannot believe this aired on Sesame Street; we used to be a proper country etc. Would love a 4K restoration of this, but Youtube is what we have for now.