Sir Isaac did not bother with the voder. "Remove thyself!"

"Eh?"

"You have brought dissension into this house. Were you not both in my house and of my family? Yet you menaced him. Please go-before you cause more sorrow."

Phipps started to speak, thought better of it-left. Don said, "Sir Isaac, I am terribly sorry. I-

"Let the waters close over it. Let the mud bury it. Donald, my dear boy, how can I assure you that what we ask of you is what your honored parents would have you do, were they here to instruct you?"

Don considered this. "I think that's just the trouble, Sir Isaac-I'm not your `dear boy.' I'm not anybody's `dear boy.' My parents aren't here and I'm not sure that I would let them instruct me if they were. I'm a grown man now-I'm not as old as you are, not by several centuries. I'm not very old even by human standards-Mr. Phipps still classes me as a boy and that was what was wrong. But I'm not a boy and I've got to know what's going on and make up my own mind. So far, I've heard a lot of sales talk and I've been subjected to a lot of verbal pushing around. That won't do; I've got to know the real facts."

Before Sir Isaac could reply they were interrupted by another sound-Isobel was applauding. Don said to her. "How about you, Isobel? What do you know about all this?"

"Me? Nothing. I couldn't be more in the dark if I were stuffed in a sack. I was just cheering your sentiments."

"My daughter," Mr. Costello put in crisply, "knows nothing at all of these things. But I do-and it appears that you are entitled to answers."

"I could certainly use some!"

"By your leave, Sir Isaac?" The dragon ponderously inclined his head; Costello went on, "Fire away. I'll try to give you straight answers."

"Okay-what's the message in the ring?"

"Well, I can't answer that exactly or we wouldn't need the message ourselves. I know that it's a discussion of certain aspects of physics-gravitation and inertia and spin and things like that. Field theory. It's certainly very long and very complicated and I probably wouldn't understand it if I knew exactly what was in it. I'm simply a somewhat rusty communications engineer, not a topflight theoretical physicist."

Don looked puzzled. "I don't get it. Somebody tucks a physics book into a ring-and then we play cops-and-robbers all around the system. It sounds silly. Furthermore, it sounds impossible." He took the ring out and looked at it; the light shone through it clearly. It was just a notions counter trinket-how could a major work on physics be hidden in it?

Sir Isaac said, "Donald, my dear- I beg pardon. Shucks! You mistake simple appearance for simplicity. Be assured; it is in there. It is theoretically possible to have a matrix in which each individual molecule has a meaning-as they do in the memory cells of your brain. If we had such subtlety, we could wrap your Encyclopedia Britannica into the head of a pin-it would be the head of that pin. But this is nothing so difficult."

Don looked again at the ring and put it back in his pocket. "Okay, if you say so. But I still don't see what all the shooting is about."

Mr. Costello answered, "We don't either-not exactly. This message was intended to go to Mars, where they are prepared to make the best use of it. I myself had not even heard about the project except in the most general terms until I was brought here. But the main idea is this: the equations that are included in this message tell how space is put together-and how to manipulate it. I can't even imagine all the implications of that-but we do know a couple of things that we expect from it, first, how to make a force field that will stop anything, even a fusion bomb, and second, how to hook up a space drive that would make rocket travel look like walking. Don't ask me how-I'm out of my depth. Ask Sir Isaac."

"Ask me after I've studied the message," the dragon commented dryly.

Don made no comment. There was silence for some moments which Costello broke by saying, "Well? Do you want to ask anything? I do not know quite what you do know; I hardly know what to volunteer."

"Mr. Costello, when I talked to you in New London, did you know about this message?"

Costello shook his head. "I knew that our organization had great hopes from an investigation going on on Earth. I knew that it was intended to finish on Mars-you see, I was the key man, the `drop box,' for communication to and from Venus, because I was in a position to handle interplanetary messages. I did not know that you were a courier-and I certainly did not know that you had entrusted an organization message to my only daughter." He smiled wryly. "I might add that I did not even identify you in my mind as the son of two members of our organization, else there would have been no question about handling your traffic whether you could pay for it or not. There were means whereby I could spot organization messages-identifications that your message lacked. And Harvey is a fairly common name."

"You know," Don said slowly, "it seems to me that if Dr. Jefferson had told me what it was I was carrying-and if you had trusted Isobel here with some idea of what was going on, a lot of trouble could have been saved."

"Perhaps. But men have died for knowing too much. Conversely, what they don't know they can't tell."

"Yes, I suppose so. But there ought to be some way of running things so that people don't have to go around loaded with secrets and afraid to speak!"

Both the dragon and the man inclined their heads. Mr. Costello added, "That's exactly what we're after-in the long run. That sort of a world."

Don turned to his host. "Sir Isaac, when we met in the E Glory Road, did you know that Dr. Jefferson was using me C as a messenger?"

"No, Donald-though I should have suspected it when I learned who you were." He paused, then added, "Is there anything more you wish to know?"

"No, I just want to think." Too many things had happened too fast, too many new ideas- Take what Mr. Costello had said about what was in the ring, now-he could see what that would mean-if Costello knew what he was talking about. A fast space drive, one that would run rings around the Federation ships... a way to guard against atom bombs, even fusion bombs-Why, if the Republic had such things they could tell the Federation to go fly a kite!

But that so-and-so Phipps had admitted that all this hanky-panky was not for the purpose of fighting the Greenies. They wanted to send the stuff to Mars, whatever it was. Why Mars? Mars didn't even have a permanent human settlement-just scientific commissions and expeditions, like the work his parents did. The place wasn't fit for humans, not really. So why Mars?

Whom could he trust? Isobel, of course-he had trusted her and it had paid off. Her father? Isobel and her father were two different people and Isobel didn't know anything about what her father was doing. He looked at her; she stared back with big, serious eyes. He looked at her father. He didn't know, he just didn't know.

Malath? A voice out of a tank! Phipps? Phipps might be kind to children and have a heart of gold, but Don had no reason to trust him.

To be sure, all these people knew about Dr. Jefferson, knew about the ring, seemed to know about his parents-but so had Bankfield. He needed proof, not words. He knew enough now, enough had happened now, to prove to him that what he carried was of utmost importance. He must not make a mistake.

It occurred to him that there was one possible way of checking: Phipps had told him that Malath carried the other half of the same message-that the ring carried only one half. If it turned out that his half fitted the part that Malath carried, it would pretty well prove that these people had a right to the message.