In his book, Sacks investigates various cases of children growing up without language, how they cope (or don't cope) with it, how they finally acquire language (if they do), and how differently they see the world in both the pre-linguistic and post-linguistic states. Hauser was one of the most famous cases of this sort, Helen Keller was another.
Reading this book inspired me to learn sign language, which I expected to be radically different from spoken and written language, and more powerful in many ways, as you can physically describe things in ways that has little parallel to spoken and written languages.
 - https://en.wikipedia.org/wiki/Kaspar_hauser
 - https://en.wikipedia.org/wiki/The_Enigma_of_Kaspar_Hauser
 - https://www.amazon.com/Seeing-Voices-Oliver-Sacks/dp/0375704...
 - https://en.wikipedia.org/wiki/Helen_keller
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