“The fact that metaphors can sleep and wake is both bad news and good news for speakers and writers who want to avoid mixed metaphors. The bad news is that when a metaphoric word or phrase is sleeping for us, we probably won’t notice if we use the word or phrase in ways that are inconsistent with its source-domain meaning.” Dead Metaphor Book:Mixed Metaphors: Their Use and Abuse Source: Mixed Metaphors: Their Use and Abuse
“Of course, the ‘living/dead’ nomenclature is itself a metaphor, in that it personifies metaphors as living beings that can ‘live’ and ‘die’. Like all metaphors, this personification metaphor is helpful in some ways but imperfect in others. It is useful because it allows us to think about ‘living’ metaphors as having some of the traits of living beings. That is, ‘living’ metaphors can be thought of as active, having effects, and able to cause changes. The personification metaphor also lets us effortlessly reason that ‘dead’ metaphors will not have effects or instigate changes. Nonetheless, in other respects the metaphor misrepresents the actual situation, because metaphors can be partly dead and partly alive.” Dead Metaphor Book:Mixed Metaphors: Their Use and Abuse Source: Mixed Metaphors: Their Use and Abuse