I know a walking corpse who'd spit icicle dagger to slit throat
This line provides us with an example of some of the classic imagery Aesop tends to give us. The phrase walking corpse is an idiom used to describe someone who is clearly not functioning correctly on the inside—whether it be emotionally, intellectually, or physically—but still has the ability to go about their day to day lives to some extent. Also..think zombies
More than likely, Aesop is referring to the emotional side of it since, this particular walking corpse will spew out hate without hesitation; something many unhappy people tend to do. He shows this with the image of spitting icicle daggers. They speak cold words with the intention of hurting others they see as being happier than them. This is a common characteristic of the human psyche; bring others down to your level.
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