[Meaning] untaught.[1]
"Justinus was ignorant of letters altogether and was, in a word, unlettered".[2]
Also, "you are ignorant and idle and have not even treaded Aesop".[3] In reference to idiots. The [verb] path=sai ["to tread"] [is] equivalent to to be familiar with; just as we speak of "arriving" somewhere. And again Aristophanes [writes]: "speak in a simpler and clearer way". From the proverb, "talk to me more clearly and more simply."[4]