Change is a lesser-known but deeply unsettling short story by the Welsh author Arthur Machen, a writer who profoundly influenced H. P. Lovecraft with his blending of cosmic horror and ancient mysticism.

The story is narrated by an unnamed, ordinary man whose perception of the world is subtly and frighteningly altered after a seemingly mundane, yet profound, experience. His transformation begins when he witnesses a group of people in the city engaged in an act that strikes him as impossibly grotesque and terrifying, an event that seems to peel back the surface layer of reality.

The narrator's new vision of the world is not one of ghosts or monsters, but of fundamental cosmic dread:

• The Unveiling of Horror: He begins to perceive the mundane elements of daily life, the faces of strangers, the architecture of the city, the very laws of physics, as terrifying, impossible mockeries. He senses that the world is merely a fragile, shifting illusion and that the reality underneath is a realm of unimaginable evil and decay.

• Cosmic Delusion: The fear is not of something out there, but of the change within himself, a maddening "gnosis" that grants him a brief, horrifying glimpse of the universe as a monstrous, ever-transforming entity. This revelation pushes him to the brink of sanity, as he realizes that everything he once knew is a lie, and that the only true constant is an underlying, shapeless terror.

Change is a quintessential piece of early weird fiction, showcasing Machen's signature style of deriving terror not from gore or violence, but from the sudden, profound, and intellectual realization of a corrupt cosmos concealed by the veil of everyday life.