Monastic sign languages have been used in Europe from at least the 10th century by Christian monks, and some, such as Cistercian and Trappist sign. Unlike deaf sign languages, they are better understood as forms of symbolic gestural communication called sign lexicons. Travelling Franciscan monks used finger alphabets, possibly as memory aids for preaching, and in Benedictine monasteries, signs representing words were used for limited communication when silence was required.
