He who is skilled at traveling leaves neither tracks nor traces; He who is skilled at speaking is flawless in his delivery; He who is skilled in computation uses neither tallies nor counters; He who is skilled at closing things tightly has neither lock nor key, but what he closes cannot be opened; He who is good at binding has neither cord nor string, but what he binds cannot be untied. For these reasons, The sage is always skilled at saving others and does not abandon them, nor does he abandon resources. This is called “inner intelligence.” Therefore, Good men are teachers for the good man, Bad men are foils for the good man. He who values not his teacher and loves not his foil, Though he be knowledgeable, is greatly deluded. This is called “the wondrous essential.”