Levinson is a “first-rate mathematician” at MIT who acts as a “sounding board and father substitute” to John Nash. Like William Ted Martin, Levinson’s Communist past is revealed during the McCarthy years; nonetheless, Levinson remains the “most respected member” of the math department, a “thoughtful, decisive,” and empathetic leader who becomes a “role model” for Nash. Levinson defends Nash after Nash begins to suffer psychotic episodes and exhibits erratic behavior that leads to his resignation from MIT; he later attempts to recruit Nash back to MIT.