A shrub of the Vitex tribe, called agnos
(chaste) by the Greeks, because the Athenian ladies, at the feast of
Ceres, used to strew their couches with vitex leaves, as a palladium of
chastity. The monks, mistaking agnos (chaste) for agnus
(a lamb), but knowing the use made of the plant, added castus to
explain its character, making it chaste-lamb. (For another similar
blunder, see I.H.S.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
