The word stone is an image that is used to explain the intense silence of the person. In this way, metaphors are used in poetry to explain and elucidate emotions, feelings, relationships other elements that could not to described in ordinary language. Poets also use metaphor as a way of explaining or referring to something in a brief but effective way. A simile compares two things in a clear fashion. Another example of a simile would be to say that the man is so fierce that he is like a tiger.
Metaphor works on many levels in poetry.
The best way to show how a metaphor function is to study the use of sustained metaphor. Sustained metaphor refers to a metaphor that consistently runs through the entire poem and is therefore easily identifiable. My youth is bent by the same wintry fever. The first stanza or section clearly states the central metaphor of the poem. The poem initiates a relationship between the force of nature and life force within flowers and trees and the life force that flows through humans.