Final answer:
The sentence 'The sky was a vault overhead, empty of all treasure save wonder' is an example of metaphor.
Step-by-step explanation:
The sentence 'The sky was a vault overhead, empty of all treasure save wonder' is an example of metaphor. A metaphor is a figure of speech that compares two unlike things by saying that one thing is another thing. In this sentence, the sky is compared to a vault, emphasizing its vastness and emptiness. The phrase 'empty of all treasure save wonder' adds a poetic and imaginative quality to the description of the sky.
Learn more about Types of figurative language