Answer:
I start in little but I end in full, you'll find me in half and complete.
They come to witness the night without being called, a sailor's guide and a poet's tears. They are lost to the sight each day without the hand of a thief.
What is used by man, tossed by trees, everywhere but unseen?
What age most travelers have?
Pointing North, South, East, and West it saves the lost and helps the rest. What is it?
What is always coming but never arrives?