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From 《资治通鉴·唐纪》: Tang empress Wu Zetian's cruel official Lai Junchen 来俊臣 asked the equally cruel Zhou Xing 周兴 how to make stubborn suspects confess. Zhou suggested heating a large earthenware jar and forcing the suspect inside. Lai then revealed he had been ordered to interrogate Zhou himself, 'Please, sir, step into the jar.' Zhou confessed at once.
