Intelligence is the first and foremost basis for the universe of knowledge. Therefore, the essence of thought and intelligence is human's most fundamental question. Illuminating the essence of reasoning, the author has made an attempt to present an answer to this question that how intelligence can asses and review itself, as it assesses and reviews others, and how far it can proceed to passing judgments on itself. The author claims the assessment of intelligence by intelligence is plausible and possible. Furthermore, the reason has criticized reason on its own. This self-assessment is the exclusive trait of intelligence and no other recognition system benefits from this advantage.
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