In what ways do you see changes in John Nash’s personality throughout the second third of the movie?

At the open of A Beautiful Mind, John Nash is presented as a promising young student who has returned from World War 2. Although he has trouble with other students, specifically Hansen, he shows himself to be a brilliant and put-together student in college. He is constantly hounded by the possibility that he is not as good as other students; this is amplified in the beginning by scenes like the game of Go that he plays against Hansen. He thinks differently and is shown to the audience as a person that thinks outside the box—“Classes will dull your mind, destroy the potential for authentic creativity”—this quote is meant to show the fact that he is a genius, and sets up his eventual success in finding unknown equations and ideas. In the first third of the movie, he is able to write a high-level critique of Adam Smith’s The Wealth of Nations which highlights how promising his future is at the start of the movie.
In the second third of the movie, we see the peak of his initial brilliance. Nash is offered a spot at MIT based on his new theory developed in the bar. He makes friends with the other mathematicians, finds love with his wife, and is eventually offered a position at the Pentagon cracking enemy codes during the cold war. However, the success we see in the middle of the movie begins to erode as Nash’s schizophrenia begins to show itself in his life.
At the beginning of the movie and through his success Nash has promising potential, while quirky his theories make sense and he seems put together as a person. As his paranoia and schizophrenia begin to take their toll he loses it. He stops dressing up and is seen at work without his normal suit and tie. That outward change is accompanied by, and really represents, the internal struggle he feels because of his increasing confusion and worries about secret Soviet agents chasing him. His life falls apart as a result of his hallucinations and paranoia and eventually comes to a climax when he punches Dr. Rosen at his guest lecture at Harvard.
His rise and fall in the first two-thirds of the movie are what make his eventual struggle more meaningful in the last third of the movie. We as the audience feel more connected to him because we have followed his progress and empathize with his struggle.
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