Details on common expressions in monastic sign language / 11th cent
Still, there are strong indications that early medieval monasteries were not always as silent or as calm as they should have been. The central social role that monastic houses played in local affairs meant that they received a steady influx of visitors—and their noise.
However, this did not mean that "absolute" silence unattainable.
To avoid breaking the silence or disrupting a mandatory activity, such as reading during a meal, 10th-century monks and nuns developed a sign language. This was known as the monasteriales indicia, or, the monastic signs. This sign language made it possible to maintain a complex discussion without disturbing the sacred silence of the monastery. Here is an excerpt from a manuscript explaining how to ask for soap using the monasteriales indicia: by rubbing one's hands together.