Troubled Sole

Last week I saw a single shoe lying by the side of the highway. Today, I saw a different shoe sitting all lonesome in the playground. There is something about lost single shoes that invites questioning.. there must be a story behind each one. How did shoe wearer person manage to lose just ONE shoe? Didn't their foot feel cold, or wet, or at the least different from the shoed foot?
I find it troubling, to say the least.