Personification. Because it used human quality on the valley
The type of figurative language is idiom
Answer and explanation:
This is a quote by Robert Frost taken from his poem "The Secrets Sits", and the interpretation we can come up with after reading it, is that we (humans) spend a large part of our lifetime stressing over things that won't matter on our last days (being material things for example) and in that sense we keep "dacing round in a ring" while contemplating. Then at the center (the middle) of our lives there is a huge power that we do not comprehend and we, humans, can only try to guess what this power means.
