The master performers and playwrights Kan'ami and Zeami, father and son, develped a unique form of masked theatre in the late 14th century, under the active patronage of the emperor Yoshimitsu. The conventions of Noh evolved in the late 14th centuries out of shamantic Kagura festivals of the Shinto faith, ceremonies for the dead, and the popular masked entertainments of Sarugaku and Dengaku. Zeami especially is credited with adding a focused concern with zen Buddhist philosophy and a stately decorum. Stories often involve an encounter that reveals an unresolved issue in the past, and the masks are worn only by the principle actor, or Shite, who unfolds the tale, frequently wearing two masks in sequence - the second of which reveals the crux of the matter. Originally, there would be five Noh plays given: a god play, a warrior play, a "wig" play centering around a beautiful woman, a "miscellaneous" play based on contemporary events or incidents of madness, and a play about demons and supernatural beings. These plays focused on the lingering ghosts of past events would be alternated with comedic Kyogen plays based on events in the contemporary world and sometimes using whimsical masks for gods, demons and clowns. The entire evening and the units within it proceed by a "jo-ha-kyu" structure: opening, intensifying, and releasing. Some of the old Noh masks are among the most beautifully finished and subtely expressive masks ever made.