The rolling vessel

Quick, quick, roll the vessel, came the order.
Roll, roll it, to gather the moss.

Hmm, exceedingly familiar that does sound.
But deep from the memories of early days in school,
came the now not-oft quoted line:
an empty vessel gathers no moss.

Of course, no moss it gathers!
For it rolls on grounds that have no moss!

Know thy terrain, one can hear the Wise One say.

No moss in the area, how to gather moss?
No wonder the vessel makes such a din as it rolls down the rocky path.