and James. Jewish, Jacob; French, Jacques, our “Jack,” and Jacquemes, our “James.” Jacques used to be the commonest name of France, hence the insurrection of the common people was termed the insurrection of the Jacques, or the Jacquerie; and a rustic used to be called a Jacques bon homme. The Scotch call Jack Jock.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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