A good runner leaves no tracks.
A good speech has no flaws to censure.
A good computer uses no tallies.
A good door is well shut without bolts and cannot be opened.
A good knot is tied without rope and cannot be loosed.
The Wise Man is always good at helping people, so that none are cast out;
he is always good at saving things, so that none are thrown away.
This is called applied intelligence.
Surely the good man is the bad man's teacher;
and the bad man is the good man's business.
If the one does not respect his teacher,
or the other doesn't love his business,
his error is very great.
This is indeed an important secret.