Answer:
It stands upright and can be quite grand. Its secret is not hidden but right at hand. What is it?
As soft as silk, as white as milk, as bitter as gall, a thick green wall, and a green coat covers me all.
I have a tongue, but do not talk. I follow close, but neither run nor walk. Coupled and hitched, but never married. You couldn't bear the load I've carried.
I heard of a wonder, of words moth-eaten. That is a strange thing, I thought, weird. That a man's song be swallowed by a worm. His blinded sentences, his bedside stand-by rustled in the night - and the robber-guest. Not one wit the wiser. For the words he had mumbled.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.