Guineas were gold coins first issued in 1663 and initially valued at £1.00. In 1717, owing to changed relative values of silver and gold, the guinea's value was adjusted to 21 shillings, i.e., £1.05. The coin was no longer minted after 1817, when it was supplanted by the 20-shilling (£1.00) gold sovereign. Ever since then, however, certain prices have been quoted in those imaginary guineas, principally because of the snob appeal (105). As for "half-guineas," they are but another example of Bunthorne's transcendental imagination. See also The Sorcerer and Princess Ida.