Imagine a child who has never seen or heard any language at all. Would such a child be able to invent a language on her own? Despite what one might guess, the children described in this book make it clear that the answer to this question is "yes".
The properties of language that we find in deaf children's gestures are just those properties that do not need to be handed down from generation to generation, but can be reinvented by a child de novo -- the resilient properties of language. This book suggests that all children, deaf or hearing, come to language-learning ready to develop precisely these language properties.