The basic impoverishment of deafness is not lack of hearing but lack of language. To illustrate this, we have only to compare a 4-year-old hearing child, with a working vocabulary of between 2,000 and 3,000 words, to a child of the same age, profoundly deaf since infancy, who may have only a few words at his command. Even more important than vocabulary level, however, is the child's ability to use his language for expressing ideas, needs, and feelings. By the age of 4 years, the hearing child in all cultures has already grasped the rules of grammar syntax that enable him or her to combine words in meaningful ways. (Contains 2 notes.)