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.
If I were travelling with two partners, one virtuous and one dishonest, both would be useful as teachers. I would perceive what's good of the first one and I would imitate him whereas I would try to correct in me the defects I may see in the second one.
Some are born with knowledge, some derive it from study, and some acquire it only after a painful realization of their ignorance. But the knowledge being possessed, it comes to the same thing. Some study with a natural ease, some from a desire for advantages, and some by strenuous effort. But the achievement being made, it comes to the same thing.
We can know a person by observing his behaviour, understanding the reasons for his actions and ascertaining his intentions. If we do this, how can we not know him?
There are 3 elements essential in the matters of the State, Food, Military equipment, and Confidence of the people in the ruler. Of these 3, Military Equipment is the least important, Food being the 2nd important, and Confidence of the people being the MOST important. All men rather die of starvation than in war, but nevertheless all men do die of old age. Lacking in Confidence from the people, a state cannot survive.