The sages of old were so deep,
no one could fathom them.
Because their minds were beyond understanding, we must be content with describing their appearance.
Careful, like crossing a frozen stream
Aware, as though watching all around
Courteous, like a polite guest
Yielding, like ice on the verge of melting
Simple, like an uncarved block of wood.
Open, like a broad valley
Turbid, like muddy water.
Remain calm, and even muddy water becomes clear.
Remain still, and movement brings you to life.
One who follows the Way does not wish to be always full;
For this reason he can pass through exhaustion and be replenished.
Commentary: More water metaphors in this chapter, in the context of describing a sage. A sage's mind is deep, like deep water, all we can do is describe his appearance. If there were a contest for the Ten Commandments of Taoism, this chapter would have a strong claim on the title, with its list of characteristics that make a good sage. Although these attributes of sages are suppposed to concern only their appearance, they are clearly meant to be indicative of the sage's mental state.
Why turbid like muddy water? The very next line says that remaining calm allows muddy water to become clear, presumably even for sages. The remaining lines bring to mind the Laoist idea of cycles and contrast: by focusing on moments of stillness, we are more invigorated by movement. By not wishing always to be happy, we are able to pass through periods of unhappiness more easily. This idea will be instantly familiar to anyone who's been troubled by insomnia, which often stems from an obsession with getting enough sleep. If we believe we can't tolerate sleepless nights, our fear of not being able to get enough sleep keeps us awake and torments us. But if we accept that some days we will feel rested, and some days tired, we can relax and take life as it comes.