How deaf education and artificial language were linked in the 17th century
Before the 1550s, it was generally believed that people who are born deaf are incapable of learning a natural language such as Spanish or English. This belief was nourished by the observation that hearing children normally acquire their speaking skills without explicit instruction, and that learning to read usually proceeds by first connecting individual letters to individual speech sounds, pronouncing them one by one, before a whole word is read and understood.