In my writing nuggets, Ron Rozelle tells us aspiring novelists that a metaphor is an implied analogy - it suggests a similarity without actually saying that the simialirty exists. It makes your reader think of a thing or an action that is not the thing or the action that you are describing.
Ron suggests that its much like a wine expert saying that a particular vintage has hints of berries or melons or pepper. These things aren’t actually in the wine, but they help give the reader imagine what it will taste like. You’ll use similes in many of the places were you may have chosen to use a metaphor but they will be stated resemblances rather than implied ones using ‘like’ or ‘as’.
A metaphor could say the burglar moved little cat’s feet whereas a simile will say he moved like a cat or as a cat.
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