Bun Bu Ryo Do: “The pen and the sword in accord”
Before the 14th century, samurai were generally illiterate, rusticated brutes; they did, however, aspire to the more cultured abilities of the nobles in time.
Beginning around the fourteenth century, Samurai were expected to be cultured and literate. But few Samurai warriors had the time or inclination to dedicate their already difficult lives to such pursuits.
So a very small minority achieved the ideal and lived their lives as a true Samurai.