The original concept of the "Music of the Spheres" is credited to Pythagoras (c.569-475 BC), a musical-mathematical-mystic, but its first surviving written account appears in Plato (c.427-347 BC). At the end of his Republic, Plato gives a tour of the afterlife and a view of the planetary spheres. But for Plato they aren't true spheres, they are giant "hemispheres", nested inside of each other with just the rims exposed, all rotating on a spindle of light. A Siren is assigned to each rim, singing a single note. In short, in Plato's view, the Cosmos is an enormous glass armonica in the sky! If Plato's Sirens had merely touched the hemispheres' rims with moistened fingers instead of singing, we'd be crediting Plato with the invention of the glass armonica instead of Benjamin Franklin (1706-1790).