磨而不磷,涅而不缁
      Explanation: After grinding is not thinning, dyed black after the change. Analogy will not be affected by strong human environment.
      Usage: Complex sentence; for clause; analogy willed people from the environmental impact
      Source: Pre-Qin Confucian "Analects, XVII": "Kennedy did not say almost? Grinding without phosphorus. Do not say white or Down? Uncontaminated."