The Noh and Kyogen forms of Japanese theater were perfected during the Muromachi period (1336-1568) and (combined as Nogaku) they comprise the Japanese traditional aristocratic theater still being performed today. Although they evolved alongside each other, sharing various theatrical elements and being performed together on the same stage, they are separate forms. Their actors' training programs, which usually pass from generation to generation within a family, are different, and actors of one form do not perform the other. Noh (literally, skill or ability), the lyrical traditional Japanese theater, draws its material from many sources and its form from ritual and folk dances. It is essentially a poetic, quasi-religious musical drama, usually without dramatic conflict. Generally, only the main actor wears a mask. The performance is accompanied by a chorus (ji utai) of six to ten actors and a musical band (hayashi) comprised of a flautist and two or three drummers. The chorus plays a narrative role or may even chant the lines of the main character. The rhythm of the drums and the tension suggested by the flute add an important element of the performance. The play is acted with very few props, on a raised, resonant, and empty stage. The second form, Kyogen (literally, ecstatic speech) comprises relatively short comic plays that serve as interludes between the serious Noh plays. The plots are based in the present, and the texts express a stylized form of the vernacular of the Muromachi period. Kyogen can evoke modes of farce, satire, tragicomedy, or various other genres that deal with the daily life of the lower and middle classes. Relationships between an ordinary man and his wife or lover, or between a master and his servant, are the most common themes in Kyogen, contrasting with the more serious appearances of ghosts, gods, and demons in Noh. An exploration of the full dramatic meaning and structure of Nogaku as the combination of Noh and Kyogen reveals these as two dichotomous forms that complement each other, with the various dramatic elements of each molded in a harmony of contrasts that create balance and dynamism. This harmony of contrasts, which I consider as one of the most important concepts of the traditional Japanese theater, originated in Chinese philosophy, which teaches that change is the main factor in cosmic existence. This notion of change taking place between two poles led to the concept that seeks to fuse contradictory elements into a unified harmony. The Chinese philosophers termed the two poles of each contrast yin and yang (in and yo in Japanese). While yang represents activity, positivity, masculinity, heat, brightness, and so forth, yin represents the opposite--passivity, negativity, femininity, coldness, darkness, and so forth. Through the interaction of these opposing principles, all phenomena of the universe are produced. Each contrast possesses two contradictory states: static and dynamic. At all times there is a harmonic balance between the two poles of each contrast, which exist side by side, creating a dynamic interaction that replaces and regenerates the other; and each of them contains a minor manifestation of the other. The Chinese concept of harmony of contrasts, adopted by the Japanese in the seventh century, was already well established by the eighth century. (1) The way of life derived from this concept is still evident today in many areas in Japan. As was the case in other areas of life, Japanese classical theater too was greatly influenced by this concept, employing not only one pair of Chinese philosophical contrasts but two. In addition to the contrast of in/yo that relates in particular to formative contrasts (dark/light, quiescence/movement, feminine/masculine, weak/strong, bent/straight, and so forth), there is the contrast of kyo (fiction, false, abstract, and empty) and jitsu (reality, real, concrete, and full). The kyo and jitsu relate to the essence of the material, and form the basis of the theatrical medium--the coexistence and dynamic interaction of two alternate worlds, fiction and reality. …