From "Manual of Muad'Dib" by the Princess Irulan

Will I have to shock him severely? she wondered. He needs shaking up—something to break him from routine .
"There could be many interpretations for your concern," Hawat said. He shrugged.
"Then you've already convicted me?"
"Of course not, my Lady. But I cannot afford to take any chances, the situation being what it is."
"A threat to my son got past you right here in this house," she said. "Who took that chance?"
His face darkened. "I offered my resignation to the Duke."
"Did you offer your resignation to me . . . or to Paul?"
Now he was openly angry, betraying it in quickness of breathing, in dilation of nostrils, a steady stare. She saw a pulse beating at his temple.
"I'm the Duke's man," he said, biting off the words.
"There is no traitor," she said. "The threat's something else. Perhaps it has to do with the lasguns. Perhaps they'll risk secreting a few lasguns with timing mechanisms aimed at house shields. Perhaps they'll . . . "
"And who could tell after the blast if the explosion wasn't atomic?" he asked. "No, my Lady. They'll not risk anything that illegal. Radiation lingers. The evidence is hard to erase. No. They'll observe most of the forms. It has to be a traitor."
"You're the Duke's man," she sneered. "Would you destroy him in the effort to save him?"
He took a deep breath, then: "If you're innocent, you'll have my most abject apologies."
"Look at you now, Thufir," she said. "Humans live best when each has his own place, when each knows where he belongs in the scheme of things. Destroy the place and destroy the person. You and I, Thufir, of all those who love the Duke, are most ideally situated to destroy the other's place. Could I not whisper suspicions about you into the Duke's ear at night? When would he be most susceptible to such whispering, Thufir? Must I draw it for you more clearly?"
"You threaten me?" he growled.
"Indeed not. I merely point out to you that someone is attacking us through the basic arrangement of our lives. It's clever, diabolical. I propose to negate this attack by so ordering our lives that there'll be no chinks for such barbs to enter."
"You accuse me of whispering baseless suspicions?"
"Baseless, yes."
"You'd meet this with your own whispers?"
"Your life is compounded of whispers, not mine, Thufir."
"Then you question my abilities?"
She sighed. "Thufir, I want you to examine your own emotional involvement in this. The natural human's an animal without logic. Your projections of logic onto all affairs is un natural, but suffered to continue for its usefulness. You're the embodiment of logic—a Mentat. Yet, your problem solutions are concepts that, in a very real sense, are projected outside yourself, there to be studied and rolled around, examined from all sides."
"You think now to teach me my trade?" he asked, and he did not try to hide the disdain in his voice.
"Anything outside yourself, this you can see and apply your logic to it," she said. "But it's a human trait that when we encounter personal problems, those things most deeply personal are the most difficult to bring out for our logic to scan. We tend to flounder around, blaming everything but the actual, deep-seated thing that's really chewing on us."
"You're deliberately attempting to undermine my faith in my abilities as a Mentat," he rasped. "Were I to find one of our people attempting thus to sabotage any other weapon in our arsenal, I should not hesitate to denounce and destroy him."
"The finest Mentats have a healthy respect for the error factor in their computations," she said.
"I've never said otherwise!"
"Then apply yourself to these symptoms we've both seen: drunkenness among the men, quarrels—they gossip and exchange wild rumors about Arrakis; they ignore the most simple—"
"Idleness, no more," he said. "Don't try to divert my attention by trying to make a simple matter appear mysterious."
She stared at him, thinking of the Duke's men rubbing their woes together in the barracks until you could almost smell the charge there, like burnt insulation. They're becoming like the men of the pre-Guild legend , she thought: Like the men of the lost star-searcher, Ampoliros—sick at their guns—forever seeking, forever prepared and forever unready .
"Why have you never made full use of my abilities in your service to the Duke?" she asked. "Do you fear a rival for your position?"
He glared at her, the old eyes blazing. "I know some of the training they give you Bene Gesserit . . . " He broke off, scowling.
"Go ahead, say it," she said. "Bene Gesserit witches ."
"I know something of the real training they give you," he said. "I've seen it come out in Paul. I'm not fooled by what your schools tell the public: you exist only to serve."