Musical ability and general intelligence are strikingly separable

Sacks repeatedly encounters patients whose musical faculties remain vivid and precise even as other cognitive functions collapse — people with severe dementia who can still play complex pieces from memory, or individuals with significant intellectual disabilities who possess extraordinary musical recall and improvisational skill. This dissociation suggests music is processed by partially distinct neural circuitry rather than being simply a downstream product of general intelligence or verbal reasoning.

He describes this as evidence that the brain treats musical competence almost as its own specialized organ system, comparable in some ways to language, which can also survive damage that destroys other capacities. The persistence of music in advanced neurological decline is not an isolated curiosity but a recurring pattern across many unrelated cases.

Takeaway: intelligence is not one unified faculty — a person can lose vast cognitive ground while a specific, complex skill like music remains almost untouched.