Rex was born blind, with brain damage so severe it looked as though he would never walk, talk, or do much of anything. And yet he has a talent few of us can imagine. To understand Rex's brain would be to unlock mysteries of language, memory, and music.
Correspondent Lesley Stahl has followed Rex and his mother, Cathleen, for several years now; she first met them in 2003.
Rex Lewis-Clack at age eight was a study in contrasts. Blind and full of enthusiasm, Rex was unable to dress himself, or even carry on a basic conversation.
But with everything Rex can't do, he can instantly identify any note that is played for him. It's a talent only one in 10,000 people have.
But that was just the beginning of Rex's gifts at the piano.
Stahl played Rex a song he had never heard – "Do You Know the Way to San Jose" – with Rex's piano teacher singing along. Despite not being able to see the keys, Rex was able to play the song himself after a single hearing.
Rex is a musical savant, one of a handful of people in the world who share a mysterious combination of blindness, mental disability, and musical genius.
But away from the piano, Rex was a different child, easily upset and confused by basic concepts.
Does damage in one part of the brain somehow enable brilliance to develop in another part of the brain? Do these abilities lie dormant somewhere within all of us?
The savant gift remains a mystery, which drew 60 Minutes back to Rex last year to see how he has progressed.
At age 10, Rex was as charming and excitable as ever.
"It's nice to see you, Lesley. Are you having a good day?" Rex asked Stahl.
When asked what he likes to do and if he had ever been in a swimming pool, Rex said no.
"Oh, we have a swimming pool at home, Rex," his mother said.
"So, you do swim?" Stahl asked. "Yes," Rex replied.
At the piano, Rex has improved dramatically. He worked diligently, and had moved beyond repeating music into the realm of genuine creativity.
In one exercise, one of his two new teachers, Sara Banta, makes up a run of music, and Rex has to instantly offer a musical response. "Some days we get a volley that goes on for a long time, you know, like a tennis volley," explains Banta.
Banta says the exercise is real improvisation.
Asked whether he is just making up his musical responses, Rex said, "Yes, Lesley," with a laugh.