"The Lord is my Shepherd"

I am a shepherd without a flock,

a comet without a trail,
fire without smoke,
a ship without a sail.

Or maybe I'm a sail without a ship,
a direction without a vessel,
an engine without a plane,
a bridge without its trestle.

Or maybe I'm a pen with fresh ink,
waiting for the Nile when it floods,
'til then, exercising word banks
and drawing vials of my blood.