More than halfway through this epic tale of the Knight of the Rueful Figure.
If I had to sum them up, I'd say Sancho Panza was the kind of man who mostly thought about what was in front of him and little else (maybe his wife and children, but that's about it). He follows Don Quixote because it never occurs to him that the man is crazy (later it does, but it's too late; by then he has come to love the man). He has the foolishness of a child, a fairly cunning one, and the wisdom as well, in that he values simplicity and honesty above all.
Don Quixote, surpisingly, is rather clear-eyed; you can talk to him about a number of subjects and he'll reply as cogently and intelligently as any sane person. The problem is what he considers important. He may know about the world around him but what matters is the world beyond that world, of knight errantry and dragons and enchantments and whatnot. The rest is there, but irrelevant. As for wisdom, needless to say his is the wisdom of the mad, in that he values gallantry and courage above all.
So you have a simpleton who sees little except what's in front of him, and a madman who sees little except what's not in front of him. What falls in between the nearsightedness of one and farsightedness of the other is the rest of the world. And that's Cervantes' novel.
I'd say he's in the league of Shakespeare, perhaps stranger; he plays more intricate metaphysical games.