Sancho, when a man knows not how to read, or is left-handed, it argues one of two things; either that he was the son of exceedingly mean and lowly parents, or that he himself was so incorrigible and ill-conditioned that neither good company nor good teaching could make any impression on him.
In Miguel de Cervantes' "Don Quixote," the character reflects on the implications of a man's inability to read or being left-handed. The statement suggests that such traits may indicate one's family background, pointing to potentially lowly or poor parental influence. Alternatively, it could signify that the individual is inherently troublesome or resistant to improvement, indicating a deeper personal flaw.
This perspective sheds light on societal attitudes towards education and personal development during the time. It implies that a lack of education or deviation from norms, like being left-handed, could reflect negatively on one's character and upbringing, leading to judgments about worth and capability.