This point can be highlighted further by briefly considering Nash's achievement in relation to game theory. It must be noted that Nash did not develop game theory on his own. He developed an original idea, but this idea was then built upon and developed by other theorists. This is explained in The Essential John Nash, saying that "Nash provided the foundations for the analysis, while Selten developed it with respect to dynamics, and Harsanyi with respect to incomplete information" (Nash 3). Considering that Nash originally pioneered the idea of game theory when he was 21, the question is raised as to why Nash never achieved anything more. Since the basic ideas behind game theory were his, why wasn't Nash the one further developing game theory and finding out how to apply it? The answer is that Nash's schizophrenia made him incapable of contributing anything further. This also explains why Nasar goes into detail about Nash's accomplishments and how the game theory had a significant impact for years to come, but does not provide any details of any further accomplishments. As Nasar describes the impact of game theory, it can sometimes appear like Nash continued achieving for decades. In reality, he made his one major contribute to mathematics when he was 21. His original ideas were expanded upon to become working theories and were then applied in various areas. Despite how long the theories continued to impact mathematics and economics, Nash was no longer actively contributing. The reason he made no further contribution is that his schizophrenia prevented him from doing so. This illustrates that schizophrenia is not something that contributes to greatness or to creative thought. It also shows that Nash was not able to achieve because of his schizophrenia. Instead, schizophrenia ruined his capacity for greatness and for creative thought, and made him incapable of achieving anything more.