High up in the north, there sits a rock
one thousand miles wide by one thousand miles high by one thousand miles deep
Once, every thousand years, a little bird
comes to this rock to sharpen
its beak upon.
When the rock has been thus worn away, then but a single day of eternity
will have passed.
Caveat: I may have heard this from some other source, so apologies to that source if this is the case.