The dominant theme of the book is that of illness. John Forbes Nash Jr. was a mathematical genius whose career and life were marred by paranoid schizophrenia. Nash was a loner as a child and didn't relate well to others. This remained a problem throughout his life. He would belittle people and engage in inappropriate pranks. When his paranoid schizophrenic episodes began, he believed that he was being contacted by aliens from outer space who wanted him to save the world. He was trying to form a world government and contacting different embassies with this goal in mind. He would write letters in different colored inks and crayons. When he was released from this first hospitalization, he wanted to go to Europe so Alicia left their newborn son with her mother and went with him. He spent several months in Geneva, trying to renounce his American citizenship. He finally 'lost' his passport.