According to an upcoming Steve Jobs biography, Apple CEO Tim Cook once offered a sick Steve Jobs—who suffered from a side effect of cancer called ascites—a portion of his liver, but Jobs turned him down. “He cut me off at the legs, almost before the words were out of my mouth,” Cook told Brent Schlender, author of Becoming Steve Jobs. “‘No,’ he said. ‘I’ll never let you do that. I’ll never do that.’” Cook describes the encounter as an example of Jobs’s selflessness.