means “still, quiet, calm, peaceful, or tranquil” extending to “clean, modest, and soft-voiced.” In modern Chinese, qīngjìng (清靜) is used as a complex meaning simply “a quiet (place);” in the text of Língshū 1.3, qīngjìng (清靜) is rendered as a conjunction of stative verbs “is clear” and “is tranquil;” this pair of characters is used only three other times in Nèijīng, all in Sùwèn. In Sùwèn 3, line 6.4, and we include the prior phrase of that line for context:
清靜則肉腠閉拒， 雖有大風苛毒，弗之能害， 此因時之序也。
Therefore, as for wind, it is what initiates a hundred diseases.
When one is clear (qīng) and tranquil (jìng), the flesh and còu[lǐ] are closed and resist against [wind]. Even if one has [been exposed] to great wind or severe poison, these [afflictions] are not able to cause harm, because of the rhythm of the timing [of wèiqì].
The other two times this expression, qīngjìng (清靜), occurs in Nèijīng are in the middle of very long chapters on 五運六氣 (wǔyùn liùqì). One of those is in a brief passages in Sùwèn, chapter 74, which is quite straight-forward, and easy to understand, so I copy it here:
In people, as for the qì of yīn-yáng, when one is clear (qīng) and tranquil (jìng), then the transformations (huà) of life are [properly] governed (zhì); when it is shaken (dòng), then severe illness arises. The saying is such.