Answer:
Bright as diamonds, loud as thunder, never still, a thing of wonder. What am I?
By Moon or by Sun I shall be found. Yet I am undone if there's no light around.
I move without wings between silken strings. I leave as you find my substance behind
I am an instrument capable of making numerous sounds but cannot be touched or seen. What am I?
A trail, a union, together tied. Come across me and you will find you cannot change the course I'm on. Without me you cannot travel on. What am I?
What is always coming but never arrives?