Isaac read his silence as submission. Given more time, Daniel might have disabused Isaac of any such ideas, and extricated himself. But a servant was knocking at the door. A minute earlier Daniel had heard someone calling briefly at the front door of the house, presumably to deliver a message, and now it had penetrated to the study, and interrupted their discourse at the worst possible moment for Daniel. He wondered whether the servant had been lurking outside the door, waiting to knock at some subtle signal from Isaac: I have sprung the trap, now interrupt us lest he wriggle free!