Bonet put into practice the “combined” system of teaching the deaf to speak and the dumb to communicate with others. He showed how the deaf could be taught to speak by reducing the letters to their phonetic value, and he advocated the use of finger-spelling. It is probable that he learned his system from Pedro Ponce de León (1510-84), another Spaniard, whose writings have been lost. English translation: Simplification of the letters of the alphabet: And method of teaching deaf-mutes to speak (1890). Digital facsimile of the 1620 edition from Google Books at this link.