What adds to the flatness of the play is a device which Diderot introduced on a deliberately adopted principle; we mean the elaborate setting out of the acting directions.  Every movement, every gesture, every silent pause is written down, and we have the impression less of a play than of some strangely bald romance.  In the versified declamation which then reigned on the French stage, nothing was left to natural action, nothing was told by change of position, by movement without speech, or in short by any means other than discourse.  Diderot, repudiating the conventions of dramatic art, and consulting nature or reality, saw that there are many scenes in life in which it is more natural to the personages of the scene to move than to speak, in which indeed motion is natural, and speech is altogether unnatural.  If this be so in real life, he said, it should be so on the stage, because nothing passes in the world which may not pass also in the theatre; and as pantomime, or expression of emotion, feeling, purpose, otherwise than by speech, has so much to do in life, the dramatist should make abundant use of pantomime in composing stage-plays.  Nor should he trust to the actor’s invention and spontaneous sense of appropriateness.  He ought to write down the pantomime whenever it adds energy or clearness to the dialogue; when it binds the parts of the dialogue together; when it consists in a delicate play that is not easily divined; and almost always he ought to write it down in the opening of a scene.  If any one is inclined to regard this as superfluous, let him try the experiment of composing a play, and then writing the pantomime, or “business,” for it; he will soon see what follies he commits.[257]

Whatever we may think of the practice of writing the action as well as the words for the player, nobody would now dispute the wisdom of what Diderot says as to the part that pantomime fills in the highest kind of dramatic representation.  We must agree with his repeated laments over the indigence, for purposes of full and adequate expression, of every language that ever has existed or ever can exist.[258] “My dear master,” he wrote to Voltaire on the occasion of a performance of Tancred, “if you could have seen Clairon passing across the stage, her knees bending under her, her eyes closed, her arms falling stiff by her side as if they were dead; if you heard the cry that she uttered when she perceives Tancred, you would remain more convinced than ever that silence and pantomime have sometimes a pathos that all the resources of speech can never approach."[259] If we wonder that he should have thought it worth while to lay so much emphasis on what seems so obvious, we have to remember that it did not seem at all obvious to people who were accustomed to the substitution of a mannered and symmetrical declamation for the energetic variety and manifold exuberance of passion and judgment in the daily lives of men.