I read this recently in the National Geographic Magazine May 2017 cover story "Genius" by Claudia Kalb:
But when he sits down in front of audiences, he purposefully pushes notes out of his mind, moving his hands to keys he had no intention of playing. "I'm bypassing the brain completely," he tells me. "I am being pulled by a force that I can only be thankful for." Jarrett specifically remembers one concert in Munich, where he felt as if he had disappeared into the high notes of the keyboard. His creative artistry, nurtured by decades of listening, learning and practicing melodies, emerges when he is least in control. "It's a vast space in which I trust there will be music," he says.
Read the article here.