神妙莫测

Explanation: Unpredictable: You can not guess, measure. Describe the wonderful extreme. 　　Source: Liu Baiyu "three-day Yangtze River": "Gap in the strong sunshine and white clouds mixed one, a few steps apart, here is the sun, there are clouds, really marvelous and unpredictable." Thesaurus:  Haunted impermanence, Surreptitious Unpredictable, appear and disappear mysteriously