What metaphors are used in Farewell to Manzanar by Jeanne Wakatsuki Houston?

The reference here is to the stones that members of the internment camp has spent time looking for, polishing and turning into a rock garden or a pathway. Many of these human constructions remained intact through the decades after the closure and release of the internees and in the process served to become a metaphorical voice capable of speaking about the power of perseverance and the endurance of the human will to survive intolerable cruelty.

“Each stone was a mouth, speaking for a family”