Linguistic relativity, otherwise known as the Sapir-Whorf hypothesis, holds that language either controls thought (linguistic determinism) or merely influences it (linguistic probabilism.)
While I am not convinced language enables thought, even if this were the case it would not rule out personalized languages developed by a single individual that enabled her or him to engage in inner dialogue but could not be used in conversations with others, and perhaps could not even be verbalized or expressed in writing. I have experienced thinking in imagery, for instance, and one girl I know has claimed to sometimes think in colors.
If we take the Buddhist perspective and consider the mind a sense organ in and of itself, perhaps such personalized languages arose as a form of synesthesia. They describe a “mixing of the senses” whereby one sense is experienced as another. Taste is translated into shapes, for instance. Among those who share this or that form of synesthesia, however, there would not be a naturally shared language. Spicey might be seen as a triangle for one, a square for another. Metaphor, analogy and so on, such as that used in poetry, is often spoken of as if it were a form of synesthesia and may even suggest such a personalized language.
Given that, perhaps dreams are speaking to us clearly after all, it is only that they are doing so in our native, inner-tongue. Being conditioned to use our shared, cultural lingo as a default has simply made inner-lingo significantly less comprehensible.
We internalize our shared, cultural language out of convenience. Rather than having to stop and translate self-talk, we save time and energy. With more value placed in the herd than in the individual, with personal forms of language inaccessible to the herd, the herd would not find much value in it and referencing such rogue manners of thinking may even be seen as tantamount to heresy or treason. People bark at foreigners to “learn the language,” after all, and the language being condemned is a shared one from another culture. Inner-lingo, one might imagine, would spawn prejudice of even greater intensity.
Shared language limits what we are able to think and the connections that can be made between lingo-bound thoughts and the ways in which they can be connected. Some words are not translatable in another language, and things are always lost in translation regardless — plays on words, cultural references, allusions, metaphors, euphemisms, expressions.
Are the bilingual, the multilingual, able to think thoughts that the monolingual simply are not equipped to think — or perhaps only unable to share? Does a subliminal undercurrent of inner-lingo persist, however neglected — and might dreams be one example of this? The visual arts?
There may be other suggestions of inner-lingo as well — after all, we can know what we want to say but not be able to find the words to say it. And if I “cannot find the words to describe” something though know what and how I want to describe it, does that not suggest the presence of another language in my head that I am unable to convey through speech or translate onto the page?
All of this seems to suggest that, if nothing else, we possess another language, however unconscious, and we may all speak to ourselves in our own unique, native tongue — each mind Greek to the other and perhaps, under the influence of culture, even to itself.