a figure of speech in which a similarity between two things is highlighted by using a word to refer to something that it does not literally denote — as when Shakespeare wrote, "All the world's a stage."
When Shakespeare wrote, "All the world's a stage, And all the men and women merely players." he was not saying the world is really a stage and all people are actors. But he was pointing to the similarities he wants us to recognize.
Quincey's head is level at times, but most so when there is to hunt, metaphor be more dishonour to science than wolves be of danger to man.