The ancient masters were subtle, mysterious, profound, responsive. The depth of their knowledge is unfathomable. Because it is unfathomable, All we can do is describe their appearance. Watchful, like men crossing a winter stream. Alert, like men aware of danger. Courteous, like visiting guests. Yielding, like ice about to melt. Simple, like uncarved blocks of wood. Hollow, like caves. Opaque, like muddy pools.

— Tao Te Ching – Chapter 15

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