Because the newer methods of treatment are good, it does not follow that the old ones were bad: for if our honorable and worshipful ancestors had not recovered from their ailments, you and I would not be here today.
When a man's knowledge is sufficient to attain, and his virtue is not sufficient to enable him to hold, whatever he may have gained, he will lose again.
The way of Heaven and Earth may be completely declared in one sentence: They are without any doubleness, and so they produce things in a manner that is unfathomable.