I asked the poet Tony Hoagland what he thought about fear. He said fear was the ghost of an experience: we fear the recurrence of a pain we once felt, and in this way fear is like a hangover. The memory of our pain is a pain unto itself, and thus feeds our fear like a foyer with mirrors on both sides.
And then he quoted Auden: “And ghosts must do again/What gives them pain.”
Mary Ruefle, On Fear