_Lady Chiltern._ That woman who has just gone out.... Robert, I know this woman. You don't. We were at school together.... She was sent away for being a thief. Why do you let her influence you? Then after much painful probing as to why he has so suddenly changed his attitude towards the scheme, she elicits the reason. _Sir Robert Chiltern._ But if I told you---- _Lady Chiltern._ What? _Sir Robert Chiltern._ That it was necessary, vitally necessary. _Lady Chiltern._ It can never be necessary to do what is not honourable.... Robert, tell me why you are going to do this dishonourable thing? _Sir Robert Chiltern._ Gertrude, you have no right to use that word. I told you it was a question of rational compromise. It is no more than that. But Lady Chiltern is not to be so easily put off as that. Her suspicions are aroused. She says she knows that there are "men with horrible secrets in their lives--men who had done some shameful thing, and who, in some critical moment, have to pay for it, by doing some other act of shame." She asks him boldly, is he one of these? Then, driven to bay, he tells her the one lie of his life. _Sir Robert Chiltern._ Gertrude, there is nothing in my past life that you might not know. She is satisfied. But he must write a letter to Mrs Cheveley, taking back any promise he may have given her, and that letter must be written at once. He tries to gain time, offers to go and see Mrs Cheveley to-morrow; it is too late to-night. But Lady Chiltern is inexorable, and so Sir Robert yields, and the missive is despatched to Claridge's Hotel. Then, seized with a sudden terror of what the consequences may be, he turns, with nerves all a-quiver, to his wife, pleadingly-- _Sir Robert Chiltern._ O, love me always, Gertrude, love me always. _Lady Chiltern._ I will love you always, because you will always be worthy of love. We needs must love the highest when we see it! (_Kisses him, rises and goes out._) And the curtain falls upon this intensely emotional situation.