When I joined the Magic Castle in 1980, one of the treats was to sit and talk — actually, sit and listen — to Dai Vernon, one of the greatest magicians of all time and a great teller of stories. "The Professor," as some called him, invented a lot of tricks that are carried on by others and one of them is a card trick called "Triumph." Here, Daniel Roy takes us through ten levels of this trick — and at the end, he explains why it might be the greatest card trick of all time…