This is the most interesting art in this Way. There are many different kinds of madness, but the actor who has grasped and mastered this one Way should be able to portray them all. Thus I stress again that you must approach this strenuous study in all seriousness. Of the various kinds of spirits that possess others, there are gods, buddhas, wraiths of living persons, and spirits of the dead; and if you study the essence of such spirits, you should be able to communicate them easily. Parents who are searching for their children who have become separated from them, women abandoned by their husbands, men who have outlived their wives— people who have become distraught with such preoccupations are quite difficult. Even a good shite [principle actor] may not distinguish these mental states, and may act out a single general insanity, but this will give the spectator no impression at all. If, however, you grasp the cause of the madness, make the expression of those feelings your most fundamental and absolute intention, turn the madness into the Flower, and become deranged in your own mind, the impression and visual interest will be established. You should understand that if people are moved to tears with a performance of this nature, you skill has been peerless.
Zeami (The Flowering Spirit: Classic Teachings in the Art of Noh)