The Visual Modality includes those neural circuits between the receptive transducer (the eye) and the expressive transducers.
This modality has particular importance to humanity because it is through this channel that we are able to join central nervous systems with the geniuses of the past.
It is through the medium of reading and writing that knowledge in awesome quantity and detail is handed down from one generation to the next.
Writing, however, has its limitations for social interaction.
It is slow and laborious. However, another, more transient form of visual language, is highly suitable for social interaction. That is Sign Language.
There is at least one culture today that uses this modality of language exclusively--that is, of course, the Deaf Community.
They have the advantage of using a modality which includes both transient and permanent language signals.
NOTES: Get some more information on Visual Language.