My knowledge of this complicated topic is very limited, so please take this into consideration. Were does the concept of rationalism leave the blind or intellectually impaired? It is not necessarily empiric that a profoundly low IQ prohibits the recognition of a book.
The recognized, universal, standard color chart poses the question as to the validity of rationalism. If this concept were fact, how would it be possible to not impose the use of sight to identify and unify color. How could color be differentiated if it were not first "seen", consequently named and then "known" universally.