Mark what goes down with them, and what they grow restless at and cough through. It is wonderful what an index to an audience's mind their cough is. They can sit in direct draughts with their clothes wet through all the evening, and take no harm, but a prosy scene brings on an epidemic of bronchitis sufficient to lay half of them in their graves. Drama means action. A grip of the hand, a look, a sob, tells an audience more than twelve pages of dialogue could explain.
Silence is the eloquence of drama.
Avoid long speeches, especially those that have nothing to do with the play. A theatrical audience does not care twopence for poetical descriptions of moonlight, and treatises on social problems. Anyhow, keep it out of your stage-work. Harvest would have been a success, I am confident, if it had not been for the magnificent lectures on Bohemia, old age, Scotch law, and every other chance topic that happened to arise. You will find they want their drama strong.