Commentary on the Tao Te Ching (51): Those Who Know Do Not Speak; Those Who Speak Do Not Know.
Those who know do not speak; those who speak do not know. Stop their openings, close their doors; blunt their sharpness, untangle their complexities; soften their glare, blend with their dust; this is called the profound unity. Therefore, one cannot be made close to it, nor distant from it; one cannot be benefited by it, nor harmed by it; one cannot be honored by it, nor degraded by it. Thus, it is honored by all under heaven.
Commentary: Those who truly understand usually do not speak; those who speak usually do not truly understand. Block its openings, close its doors, blunt its sharpness, organize complex matters into order, harmonize with its brilliance, and blend with its worldly dust; this is called the profound unity.
Therefore, one should not become close because of acquiring it, nor should one become close because of acquiring it, nor should one gain profit because of acquiring it, nor should one suffer harm because of acquiring it; thus, it is esteemed by all under heaven.
Extension: Regardless of the matter, those who truly understand usually do not speak much to ordinary people, because it is difficult to describe. Mathematicians usually do not discuss calculus in supermarkets, nor do physicists discuss quantum mechanics with vendors while bargaining for pork. Often, those who talk loudly and expound to ordinary people are not truly understanding. To make continuous progress in cultivation, one should first identify and resolve one's own problems. In daily conduct, one should speak less and act more. At the same time, one should temper one's sharpness, humbly clarify and organize complex matters, so as to make continuous progress. In this way, one will appear like ordinary people, harmonizing with their light and blending with their dust, like a hermit who hides in plain sight. The path of cultivation should not be driven by a mindset of gain or loss. Doing so will not make one closer, nor will it bring profit, nor cause harm, nor confer honor, nor bring disgrace. It may seem that such a state of having nothing to gain or lose is meaningless, but precisely because of this, it becomes the most honored under heaven.