“My subject,” he began, “is the science of astronomy. I am going to be frank. In my land and time . . . uh . . . that is—” Guy frowned. He had warned him against any mention of that insane delusion of his about having been catapulted back from a future age. But Cambray recovered himself. “What I meant is that there are far greater masters of this science where I come from. I am familiar only with the skirts of this knowledge. Yet what I have to say will be novel to you, and will doubtless upset many of your present concepts.”