In several places in his Magnus opus, Tanya, Rabbi Shneur Zalman of Liadi makes reference to twenty two letters of thought. By this he refers to the communication which goes on inside of one’s own mind/brain. One may think that he’s referring to the conversations we have in our own heads using our native languages. At times, I considered such a possibly myself.
However, I never felt entirely comfortable with that answer because Rabbi Shneur Zalman clearly states that behavioral actions cannot occur without their first being a communication from these letters of thought. There are populations of people who don’t have a verbal language. Among them are babies and deaf mutes. Yet, they clearly act. So, by virtue of their capacity to act, they too must be in possession of these letters of thought.
So, these letters of thought cannot be referring to internal conversations in one’s own mother tongue. It must be something deeper and more innate; something shared by all humans. Today, we have technology which can serve as a model to help explain what the letters of thought possibly are.
Most people are familiar with computers. Regardless of the native language of the user, all (or at least many) computers share the same innate computer language. From this innate language, the computer forms and projects images, words, music, sounds, etc. into a medium understood by the user. For example, though the computer does not think in the user’s native language, it can communicate with the user in his/her native language.
Similarly with the human mind/brain, buried within there's likely an innate language which is hardwired into every human being. It’s likely extremely similar or even the same within every human being. This language has it’s own basic combining components which operate like letters to make words, i.e. larger units of communication. According to the Alter Rebbe there are twenty two of them, matching the number of letters in the Hebrew alphabet.
I call this language “Brainish”. As there’s English and Spanish, so there’s “Brainish”. Just like with the computer’s mind, “Brainish” also forms and projects images, words, music, sounds, etc. into a medium understood by the person’s conscious mind. From there the person can have an internal dialogue, speak with another, dream, play, act, etc.
It might be useful for the future of humanity to discover and understand how to consciously access “Brainish”, as this can go very far to increase intelligence and communication in all sorts of ways.