Hearing. A member of the Franciscian order which discouraged talking as much as possible, causing the monks to invent a variety of manual alphabets to communicate with each other without speaking. Rosselius created 3 different one-handed alphabets, the earliest ones known (previous manual alphabets used both hands, or pointed to other parts of the body instead). His work was published posthumously in Venice as Thesauras Artificiosiac Memoriae (1579). This may have influenced the development of one-handed manual alphabets in Spain.
http://www.ksl.g.se/e05rpfcr.html (Dec. 9, 1999).