Editor's Note: The main text of this story, originally published in the December 2005 issue of Scientific American , is being made available in light of the recent death of Kim Peek.

When J. Langdon Down first described savant syndrome in 1887, coining its name and noting its association with astounding powers of memory, he cited a patient who could recite Edward Gibbon’s The Decline and Fall of the Roman Empire verbatim. Since then, in almost all cases, savant memory has been linked to a specific domain, such as music, art or mathematics. But phenomenal memory is itself the skill in a 54-year-old man named Kim Peek. His friends call him “Kim-puter.”