Sometimes metaphors in novels can seem crass and unwieldy. Other times they can be sublime. But what is the difference between good and bad use?

My general rule of thumb is that deliberate metaphors should only be included if they are also a vital part of the narrative. For example, in my novel Uncle Flynn, when Max is stalked by the panther, it is an essential ongoing element of the story, without which the plot would fall apart. But the panther is also a metaphor for Max’s fears, and his responses to the panther illustrate his progress in this respect.

In Children of the Folded Valley, the trains form an equally essential part of the story. Without them the plot would simply cease to exist. And yet, the trains take on an increasingly metaphorical role as the novel progresses; lost childhood, the passing of time, the end of an era and so on.

There are a number of excellent metaphors in JK Rowling’s Harry Potter series that adhere to my above principle. For example, in Harry Potter and the Prisoner of Azkaban, Dementors are essential to the plot, but are also a metaphor for depression. In the same novel, the hippogriff Buckbeak, unjustly sentenced to death, is a metaphor for another character who has also suffered a miscarriage of justice. Again, Buckbeak is pivotal in the climax. In the final novel, Harry Potter and the Deathly Hallows, one character’s silver doe patronus symbolises their ongoing love for a deceased character – a very poignant metaphor. Patronuses are, of course, an ongoing and vital part of the series.

There are exceptions to the above rule from time to time, but generally I get irritated when a metaphor takes me out of the story and draws attention to itself when the plot could exist perfectly well without it. When that happens, I feel as though the author is deliberately popping up in the middle of the narrative to announce how clever they are. I have had many an eye-roll for this reason, often when reading critically acclaimed high-brow literature.