Why do we say "Those who know don't speak; those who speak don't know"?

Meaning:

Knowledgeable people don't feel the need to talk all the time while those who are ignorant offer an opinion on everything.

Background:

This proverb originates in China and is said to be from the mouth of the ancient Chinese philosopher and founder of philosophical Taoism, Laozi

Traditionally, Laozi is thought to have lived during the 6th-century BC, but some modern historians think that he lived about two centuries later in the 4th century BC. His name, which means Old Master, is also found translated in English as Lao-Tze and Lao-Tzu, with and without hyphen.

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