  The art in which the notion of yūgen has played the most important role is the Nō drama, one of the world’s great theater traditions, which attained its highest flourishing through the artistry of Zeami Motokiyo (1363–1443). Zeami wrote a number of treatises on Nō drama, in which yūgen (“Grace”) figures as “the highest principle” (Rimer, 92). He associates it with the highly refined culture of the Japanese nobility, and with their speech in particular, though there is also in Nō a “Grace of music,” a “Grace of performance [of different roles],” and a “Grace of the dance” (Rimer, 93). It is something rare, that is attained only by the greatest actors in the tradition, and only after decades of dedicated practice of the art. It is impossible to conceptualize, so that Zeami often resorts to imagery in trying to explain it: “Cannot the beauty of Grace be compared to the image of a swan holding a flower in its bill, I wonder?” (Rimer, 73).