Detail from the poster for Disney’s The Incredible Journey, 1963.

Yesterday, a dog raced a Metro-North train from the South Bronx into Manhattan. The train slowed down at several points so the dog, an adorable shepherd/collie mix, would not risk injury. Passengers feared for her safety during the mad dash—and cheered lustily as she was collected by two transit cops, who took her to animal control to treat her injured paw.

We love to see pets going to great lengths for our companionship, or whatever it is they’re doing. It’s hard enough to know what your dog or cat is thinking as it goes from room to room—and no one can divine the thoughts of these heroic specimens who follow their masters across continents, Incredible Journey–style. We usually choose to regard this as proof of pure devotion. But in other cases, we see these antics—especially by cats—as slightly sinister. Consider the case of “The Cat Came Back.”

Written in 1893 as a minstrel song with a very different title, “The Cat Came Back” tells of a malevolent cat who won’t stay away—until he’s killed. It’s not the sort of enlightened fare we usually associate with modern elementary education. And yet, a sanitized version of the song is a staple of nursery schools and day camps, where it’s seen as a useful tool for teaching young children about rhythm and harmony. For whatever reason, kids love the minor-key tune and the story of the grim, Mephistophelean cat.

There’s a G-rated modern version in which the owner tries to pawn the cat off on Santa Claus and an air balloon; and then there’s an earlier iteration, in which said owner clearly wants to see the feline dead. Kids laugh at both, because this cat will not be ruled by man. He defies adult authority—to say nothing of the laws of physics and geography—and this is as reassuring as it is terrifying. He “couldn’t” stay away, we are told—but not because he so loves the beleaguered Mr. Johnson, or Wilson, or whatever the owner’s name happens to be. He is a law unto himself. And the glee in telling his story has little to do with affection, and much to do with things dark and unexplained.

If no owner claims that train-loving dog, animal control is going to put her up for adoption, even though her heart is clearly wild and free and her thoughts inscrutable. But maybe for someone, that will be an adventure. Maybe they’ll like the minor key of its small mysteries. And why take on another life, if not for that?