Pliny the Younger took the story about Athenodorus and the haunted house seriously because he heard it from people he respected. But as modern skeptical investigator Joe Nickell points out, “this hearsay story…was already a century old” before Pliny shared the tale:
It had probably been retold many times, like so many folktales. It is what folklorists call a “legend”—that is, a narrative reflecting a folk belief, in this case belief in the reality of ghosts.