"I know something of mind-probing," Lanier said. He had certainly seen the techniques used enough times by magicians to extract information. "The magic is exhausting for both the magician and the subject. Even if your spell-worm is as good as you think , he won’t be able to maintain a sustained telepathic probe for very long. I also know mind-probing can be dangerous to the subject if he resists, and sometimes even if he doesn’t. Digging around in the subconscious and breaking through repressed memories can cause permanent brain damage."