 Mathematician Roger Penrose modified the argument in his first book on consciousness, "The Emperor's New Mind" (1989), where he used it to provide the basis of the theory of orchestrated objective reduction.Gödel showed that any such theory also including a statement of its own consistency is inconsistent.A key element of the proof is the use of Gödel numbering to construct a "Gödel sentence" for the theory, which encodes a statement of its own incompleteness, e.g.