涅而不缁

Explanation: Nirvana: mineral name, as the ancient black dye; http: black. Nirvana also stained with the dye is not black. Metaphor of high moral character, free from adverse environmental impact. 　　Usage: Contraction type; as predicate; with compliment 　　Source: Pre-Qin Confucian "Analects, XVII": "Kennedy did not say almost, grinding without phosphorus; not saying white peace, uncontaminated." 　　Examples: Yi Sun can be described as cold of winter, not withered, ~ who carry on. ("Book of Jin Liu Yao Records") Thesaurus:  Lightness finds, Without sediment mud