《庄子·内篇·大宗师》
能够通晓自然运化之理，是顺应自然而知；明白人的行为，是用其智力所能知道的道理，去顺其智力所不能知道的，直到享尽天年而不半途而废，这就是认识的最高境界了，虽然这样，其中还是有隐忧存在。
知天之所为者，天而生也；知人之所为者，以其知之所知以养其知之所不知，终其天年而不中道夭者，是知之盛也。
It is the following of nature and knowledge to understand the principle of nature, and it is the use of the principles known to one’s intelligence to follow the principles one’s intelligence cannot know to understand people’s actions, until the end of one’s life without interruption; this is the highest realm of understanding, although there are still hidden worries in it.