Why did Cervantes need Sancho Panza next to Don Quixote?

At first glance, it seems that Don Quixote and Sancho Panza are very different in their worldview. positions, character, appearance. Nevertheless, their sociability, love and respect for each other cannot but please. Sancho Panza also has quixotic features, although they are not noticeable at first glance. Don Quixote and Sancho Panza. embodied the best human qualities, among which, nobility, honesty and justice were the most important. They tried to restore the golden age, achieve earthly happiness for all mankind, bring spirituality and romanticism to this selfish world.
Don Quixote and Sancho Panza, in my opinion, are written as opposite characters in character and behavior. Don Quixote is a dreamer, “flying in the clouds” he thinks more about the sublime, about how to improve the world around him, and only secondarily about himself. L Sancho Panza is more down to earth, thinks first of all about himself and his immediate needs. At the same time, they also have common character traits: kindness, self-esteem, gullibility, sometimes even naivety. In general, they complement each other.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.