In Act 1, the Manager calls his play a "glorious failure"—an oxymoronic phrase that reveals his own internal conflict about the play's potential impact:
THE MANAGER. Neither do I. But let’s get on with it. It’s sure to be a glorious failure anyway. (Confidentially:) But I say, please face three-quarters. Otherwise, what with the abstruseness of the dialogue, and the public that won’t be able to hear you, the whole thing will go to hell. Come on! come on!
Moments prior, the Manager had given very abstract stage directions, and the Leading Man had claimed that he did not understand them. The Manager says that he himself does not understand them, either, but that they should all continue constructing the play. His phrase "glorious failure" could mean one of two things. The first interpretation is that the play will fail miserably but get lots of publicity and/or be deemed remarkable for the ideas within it. The second interpretation is that the play will be an abject failure, in which case "glorious" is an ironic substitution for "huge" or "great."
Of course, it is also possible that the Manager himself has no idea of what his own words mean and takes no responsibility for their significance. The Father and other family members snare him into attempting to craft a play; sometimes he seems amenable to helping them, and other times he resists wasting his time. At first, the Manager's agreeableness hinges on the play's potential success, but later in the story, he realizes that he has "lost a whole day over these people, a whole day!" Oxymoronic phrases like "glorious failure" reflect the Manager's conflicted feelings; they also sandwich two opposing terms together to create a linguistic construction that evokes the opposition between all the characters in this play.