A two-part system, the Sympathetic Diagnoser is mainly a brain implant that receives sensory information from a transmitter. The information is confined to sensations — pain, specifically, but also pleasure and fear. The transmitter is a brain scanner that another person wears on their head. When another person is wearing it, the Diagnoser allows the person fitted with the receiver implant to feel the pain (or pleasure) of the person wearing the transmitter. In “Black Museum,” the system was used to help a doctor identify the ailments of his patients by allowing him to feel them himself.