An argument to which there is no answer. Robbers in Holland at one time made use of a piece of iron in the shape of a pear, which they forced into the mouth of their victim. On turning a key, a number of springs thrust forth points of iron in all directions, so that the instrument of torture could never be taken out except by means of the key.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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