It will be noticed that Diderot made this test with regard to the appropriate gestural representation of plays that he knew by heart, but if he had been entirely without any knowledge of the plot, the difficulty in his comprehending it from gestures alone would have been enormously increased.  When many admirers of Ristori, who were wholly unacquainted with the language in which her words were delivered, declared that her gesture and expression were so perfect that they understood every sentence, it is to be doubted if they would have been so delighted if they had not been thoroughly familiar with the plots of Queen Elizabeth and Mary Stuart.  This view is confirmed by the case of a deaf-mute, told to the writer by Professor FAY, who had prepared to enjoy Ristori’s acting by reading in advance the advertised play, but on his reaching the theater another play was substituted and he could derive no idea from its presentation.  The experience of the present writer is that he could gain very little meaning in detail out of the performance at a Chinese theater, where there is much more true pantomime than in the European, without a general notion of the subject as conveyed from time to time by an interpreter.  A crucial test on this subject was made at the representation at Washington, in April, 1881, of Frou-Frou by Sarah Bernhardt and the excellent French company supporting her.  Several persons of special intelligence and familiar with theatrical performances, but who did not understand spoken French, and had not heard or read the play before or even seen an abstract of it, paid close attention to ascertain what they could learn of the plot and incidents from the gestures alone.  This could be determined in the special play the more certainly as it is not founded on historic events or any known facts.  The result was that from the entrance of the heroine during the first scene in a peacock-blue riding habit to her death in a black walking-suit, three hours or five acts later, none of the students formed any distinct conception of the plot.  This want of apprehension extended even to uncertainty whether Gilberte was married or not; that is, whether her adventures were those of a disobedient daughter or a faithless wife, and, if married, which of the half dozen male personages was her husband.  There were gestures enough, indeed rather a profusion of them, and they were thoroughly appropriate to the words (when those were understood) in which fun, distress, rage, and other emotions were expressed, but in no cases did they interpret the motive for those emotions.  They were the dressing for the words of the actors as the superb millinery was that of their persons, and perhaps acted as varnish to bring out dialogues and soliloquies in heightened effect.  But though varnish can bring into plainer view dull or faded characters, it cannot introduce into them significance where none before existed.  The simple fact was that the gestures of the most famed histrionic school, the Comedie Francaise, were not significant, far less self-interpreting, and though praised as the perfection of art, have diverged widely from nature.  It thus appears that the absence of absolute self-interpretation by gesture is by no means confined to the lower grade of actors, such as are criticised in the old lines: