The Empty Boats

Why do I see these empty boats, sailing on airy seas?
One haunted me the whole night long, swaying with every breeze,
Returning always near the eaves, or by the skylight glass:
There it will wait me many weeks, and then, at last, will pass.
Each soul is haunted by a ship in which that soul might ride
And climb the glorious mysteries of Heaven's silent tide
In voyages that change the very metes and bounds of Fate--
O empty boats, we all refuse, that by our windows wait!