How dumb is Sancho Panza?

How dumb is Sancho Panza? I would say: not at all. Certainly he's not well educated but would you suppose that there weren't many opportunities for schooling for people of Panza's social class in 17th-century Spain - education, or the deprivation of education, was the primary way through which the ruling class maintained its control of power and authority. Not until things began to change and there were opportunities for all people to make $, in the cities but not exclusively - we do see in "Don Quixote" the example of Dorotea, daughter of a wealthy farmer (and a good farmer herself), did the class structure begin to break down - and education followed inevitably. Sancho Panza, though, to me, seems to play dumb but he has a shrewd intelligence and a great deal of compassion - he's the only one who truly comprehends Quixote and knows how to protect him. Cervantes makes much of Panza's expectation to become the ruler of an island, an insula, but I think we are not meant to take this seriously - Panza reiterates this hope, but I think he does so in part as a way to maintain DQ's spirits - all he really expects is a chance to do some service, make a little money, perhaps improve his lot a bit through a new donkey or some other opportunities - and perhaps even a chance for some travel and adventure. Obviously, he's in the novel primarily as a comic foil and as a device for Cervantes to bring some perspective on DQ and his delusions - but he also serves as to maintain some balance for Quixote and as a reminder to readers that there is a whole level of social reality not accounted for in the knightly codes that DQ always cites nor in the vast storehouse of literature - up to that point - that rarely if ever included fully rendered characters from the peasantry or working class.