Horn of Fidelity

Morgan la Faye sent a horn to King Arthur, which had the following “virtue”:—No lady could drink out of it who was not “to her husband true;” all others who attempted to drink were sure to spill what it contained. This horn was carried to King Marke, and “his queene with a hundred ladies more” tried the experiment, but only four managed to “drinke cleane.” Ariosto’s enchanted cup possessed a similar spell. (See Chastity.)