This Forbes article provides a brief biographical sketch of Justice Roberts. It gives us a money-quote on how he became one of the nation's best appellate advocates in the nation's highest court.
When Roberts was preparing an oral argument, he would write down -- usually longhand, using a pen and a legal pad -- hundreds of questions that he might conceivably be asked. He'd ponder and refine the answers in his mind. Then he'd write the questions on flash cards, shuffle them, and test himself, so he'd be prepared to answer any question in any order.
In a talk to oral advocates in 2004, Roberts urged them to approach their craft with the mindset of a medieval stonemason. "Those masons -- the ones who built the great cathedrals -- would spend months meticulously carving the gargoyles high up in the cathedral," he told them, "gargoyles that when the cathedral was completed could not even be seen from the ground below. The advocate ... must meticulously prepare, analyze, and rehearse answers to hundreds of questions, questions that in all likelihood will actually never be asked by the Court. The medieval stonemasons did what they did because, it was said, they were carving for the eye of God ... The advocate who stands before the Supreme Court ... also needs to infuse his craft with a higher purpose. He must appreciate that what happens here, in mundane case after mundane case, is extraordinary -- the vindication of the rule of law -- and that he as the advocate plays a critical role in the process."