Mrs. Alving. But what is this dreadful thing--?
Oswald. You mustn't scream. Do you hear? Will you promise me that? We are going to sit and talk it over quite quietly. Will you promise me that, mother?
Mrs. Alving. Yes, yes, I promise--only tell me what it is.
Oswald. Well, then, you must know that this fatigue of mine--and my mot being able to think about my work--all that is not really the illness itself--
Mrs. Alving. What is the illness itself?
Oswald. What I am suffering from is hereditary; it--(touches his forehead, and speaks very quietly)--it lies here.
Mrs. Alving (almost speechless). Oswald! No--no!
Oswald. Don't scream; I can't stand it. Yes, I tell you, it lies here, waiting. And any time, any moment, it may break out.