The knowledge that Jackie Chan performs all of his own stunts brings a certain intensity to the act of watching his movies: A real person in real time is really doing something dangerous. There's an element of Evel Knievel to it. And also an element of Buster Keaton, because Chan is above all a silent comedian, who depends on broad humor and timing to make action comedies in which the violence is secondary ("No guns!'' he likes to shout).