TL;DR: I think while Sullivan did add context, much of the context could've been "decompression" in an almost technical sense. This would've made Helen's exact words more palatable for the world to consume, and Sullivan could've been running the same intuitive algorithm in reverse to make the broader communication of the world accessible to Helen. This probably affects other disciplines as well, e.g business.
Of course this entire premise is couched in my LLM-based reproduction of the idea, so uh, take it with a few grains of salt. I tried this on your own comment to "compress" and then "decompress" to see what the outcome is.
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I took your first paragraph starting with "After [Helen] started working with" through "high level of proficiency." and 'compressed' it as Helen's own tactile signing might've done. Did it via a temporary cgpt session. Prompted "I'm going to give you a fully formed thought. Give it back to me as if it was Helen Keller herself signing the words into Sullivan's hand. I.e if Helen didn't use filler words when signing into Sullivan's hand, don't use those words either in your reframing of this thought."
> Sullivan came. Language came.
> Soon, words rich. Thought subtle. Writing like long study. Strange. Child. New language. Yet mind seemed already full.
> Sullivan died.
> Rich words gone. Thought simpler. Same hands. Different voice.
> No second Helen.
> Others deaf-blind. Language late. Same result. Language never deep.
> Perhaps first language must come early. Speech. Sign. No matter. Miss that season. Full language may never come.
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I then, in a second, unrelated temporary session, prompted to expand the prose above into a fully formed thought. "The following is a thought conveyed via a "compressed, tactile, idea-first" language. Expand it into the full meaning that the speaker, deaf and blind, might've intended. Keep to one or two paragraphs. Do not go online."
> When Anne Sullivan entered Helen Keller’s life, language arrived with her—not merely labels for objects, but a system rich enough to support subtle thought, reflection, and writing of remarkable sophistication. That achievement was almost uncanny: Helen was still a child, newly acquiring her first true language, yet her prose often sounded as though it came from a mind already long educated. After Sullivan died, however, that richness seemed to fade. Helen still used the same hands and remained the same person, but the voice became plainer and the thought less intricate, raising the unsettling possibility that some of what appeared to be Helen’s singular literary mind had depended on Sullivan’s continual linguistic presence.
> No comparable “second Helen” emerged among other deaf-blind people who first gained language late. Their experiences seemed to point toward a critical period: perhaps the human mind must receive a complete first language early in childhood, whether spoken or signed. Once that window closes, vocabulary can still be taught and communication can still develop, but language may never become fully deep, flexible, and generative.
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My interpretation is that it's pretty similar. Even your "critical period" reference made it through compression/decompression despite the words not being present. There's some variation, and I think that supports what you're looking to convey, but it also could add weight to the idea that much of what Sullivan expressed could really have been mostly Helen's own thoughts and meanings. Of course none of this is rigorous and my entire exercise should be treated as "back of the napkin" ideation rather than actual science, but there's a thread to pull here, and it could have value in other disciplines e.g in business where intended meanings, statuses, outcomes may be preserved or lost based on how language mutates as it passes through different people.