Myth of Er - The Spindle of Necessity

The Spindle of Necessity

The myth mentions "The Spindle of Necessity", in that the cosmos is represented by the Spindle attended by sirens and the three daughters of the Goddess Necessity known collectively as The Fates, whose duty is to keep the rims of the spindle revolving. The Fates, Sirens, and Spindle are used in The Republic, partly to help explain how known celestial bodies revolved around the Earth according to Plato's cosmology.

The "Spindle of Necessity", according to Plato, is "shaped . . . like the ones we know"; id est, as the standard Greek spindle, consisting of a hook, shaft, and whorl. The hook was fixed near the top of the shaft on its long side. On the other end resided the whorl. The hook was used to spin the shaft, which in turn spun the whorl on the other end.

Placed on the whorl of his celestial spindle were 8 "orbits", whereof each created a perfect circle. Each "orbit" is given different descriptions by Plato, which no doubt represent known bodies of our solar system.

Based on Plato's descriptions within the passage, the orbits can be identified as those of the classical planets, corresponding to the Aristotelian planetary spheres:

• Orbit 1 - Stars
• Orbit 2 - Saturn
• Orbit 3 - Jupiter
• Orbit 4 - Mars
• Orbit 5 - Mercury
• Orbit 6 - Venus
• Orbit 7 - Sun
• Orbit 8 - Moon

The descriptions of the rims accurately fit the relative distance and revolution speed of the respective bodies as would appear to an observer from Earth.