Most of them are not exactly illiterate. But the ones who do not read proficiently over. Especially those in Cyrano. Since those days Education may not be the most important as it is today.
Most of them are not people do not know the book quite. But as someone who reads more than people not fluent in writing, especially in the later version of father mother because those studies might not be the most important story as today.
Most people do not know they are not writing it, but it is not a read-write smoothly, especially more than one mother because in those days, the study may not be the most important thing like today