Lao-tzu offers us this passage with the Taoist master's image penetrating from a painstaking description:

Shrinking looked they like those who wade through a stream in winter; irresolute like those who are afraid of all around them; grave like a guest (in awe of his host); evanescent like ice that is melting away; unpretentious like wood that has not been fashioned into anything; vacant like a valley, and dull like muddy water. (Tao-te ching, chapter 15, Legge version).