Two of the characters in Don Quixote who undergo significant changes are the title character and his squire, Sancho Panza. Their changes closely match Miguel de Cervantes’s themes of the importance of imagination and idealism and the influence of perception on reality.
It is worth considering that the novel begins when Don Quixote (Alonso Quixano) is already a mature man. He has actually retired from the world, but he decides to venture forth and see more of it. He is deliberately working against the bleak view of the world he had formed in his youth, and he wishes to put into play the more positive perspectives that he has gained from reading romances. At numerous points in the novel, when others encourage him to see things as they “really” are, he insists on finding noble, pure motives, even in other people’s bad behavior. He elevates what could be humdrum daily tasks to the higher plan of opposing monsters—such as seeing a giant rather than a windmill.
Sancho is initially highly skeptical of his master on every level, from his identity to his ability to pull off any heroic exploit, but he develops a deep empathy for Quixote’s sincere aspirations. Sancho knows that in supporting his master's fantastic endeavors, he is lying; his lack of guilt, however, derives from his understanding that his master depends on such beliefs for his sanity and survival. As their adventures together wind down, Sancho shows himself a true companion and regrets the loss of his friend’s idealism.