Young Jim, his father, and the mattress
The round knob and half its interior hex bolt fell off and hit my room's wooden floor with a loud noise and began then to roll around in a remarkable way, the sheared end of the hex bolt stationary and the round knob, rolling on its circumference, circling it in a spherical orbit, describing two perfectly circular motions on two distinct axes, a non-Euclidian figure on a planar surface, i.e., a cycloid on a sphere:
Context
The memoir-scene: ten-year-old Jim and his drunk father are moving a bed when the doorknob shears off and starts to roll — and the boy watches it trace a circle orbiting a circle. His father is collapsed in dust and vomit in the same room. Out of that wreckage, this is the actual physical event annulation grows from: motion that is all revolution and no progress, performed by a piece of broken hardware.