Scott

“To keep the business going, Disney moved out of his apartment and into the Laugh-O-Gram offices, where he slept on a pile of pillows. This experience also inspired his most enduring creation. “They [mice] used to fight for crumbs in my wastebasket when I worked alone late at night,” he said. “I lifted them out and kept them in wire cages on my desk. I grew particularly fond of one brown house mouse. He was a timid little guy. By tapping him on the nose with my pencil, I trained him to run inside a black circle I drew on my drawing board.” Disney named the mouse Mortimer.”
― Rees Quinn, Disney