The invention of gesture as a means of communication is as old as humanity itself, predating speech by thousands, if not millions of years. Modern sign language, however, is generally attributed to the work of the 17th-century Spanish priest Juan Pablo Bonet.
Bonet published "Reduction of Letters and Art For Teaching Mute People To Speak" in 1620, a work that is widely considered to be the first treatise describing an organized manual phonetic alphabet. Prior to Bonet's work, sign language was a piecemeal method of communication for the deaf. The development of sign languages after Bonet, including the Martha's Vineyard Sign Language and the French Sign Language introduced by Charles Epée, formalized the education and communication of deaf people.