"Why is that?" Bella asks with tones of mild curiosity.

"I'm supposed to know?"

"Well, how did you hear this warning?"

"From a reliable source."

"And this reliable source didn't tell you anything about why? Aren't you at all concerned that they just didn't want anyone else to get to use heavy-duty magic?"

"No."

"Why not?"

"Reliable reasons."

"Feel free to think so," she says. "But if you want to test it, may I suggest doing your experimenting on Mars? Less risk for the rest of us."

"These are big coins we're talking about. It would not be trivial to make an extra to test far away before using it for whatever my main project was."

"I'd pay your way to Mars and back," she offers.

This does actually bring Bella up short. "Okay, you either take this warning seriously, or you are willing to throw a lot of resources around making me think you do. Why won't you save yourself the trouble and tell me why you take it seriously?"

"I don't get the impression that 'I trust the person who told me' will carry much weight with you."

"It carries weight - in the sense that it moves the question a step further. Where did that person find out?"

"And we're back to square one."

"I'm trying to figure out why that would be a secret," muses Bella. "Would it harm the person who warned you if this fact were known in any more detail? I don't go around attacking people for issuing warnings, who would? Perhaps you just made a general promise not to spread the information, because... your warner is paranoid? You don't seem to be operating under a general principle of never sharing information, or never sharing information with me; only here and there. Maybe this is the wrong idea; maybe you don't know where the original warning came from, and you're... embarrassed to pay attention to a restriction that you don't know much about? Undertaking your own controlled experiments on an ongoing basis, and don't want me to know about it?" Bella pauses, like she's thinking of it for the first time. "Maybe the warning doesn't apply to everyone, and you don't think you'd like what I'd do with information about that, and you think I'd derive some if you were any more forthcoming."

"You're very thorough," says Libby. "Has anyone ever told you that? I bet they have."

"I'm not sure if the exact word has come up. And I'm sure I'm missing something. You're under a geas and cannot share the information because someone else has reasons of their own to keep it limited - you're trying to keep me occupied fussing about this to distract me from something else - someone has a reliable native power of prophecy and says there will be a rain of frogs if I learn the truth -"

Libby shrugs.

"Don't stop me if I get close, or anything, I might find myself inclined to like you and that would be awful."

"No rains of frogs," she says, helpfully.

"Oh, good, amphibians would be thematically inappropriate. I prefer cetaceans." Bella closes her eyes. "Is the person who told you still alive?"

"I suggest we move on to a topic you'll find less frustrating," says Libby.

"Do you think I would find moving on without knowing the answer less frustrating?"