Three coins sat in a fountain.
The first coin was thrown some hundred years before. It had sat and sat, unrealized. It glued itself to the floor, and was of no value.
The second coin was thrown the day before. It was thrown on a whim, and could not truly afford to be thrown. It had too much value, but could not be reached.
The third coin was not yet thrown, and did not exist. It waited its time, preparing to join its kin.