"The skilful traveller leaves no traces of his wheels or
footsteps; the skilful speaker says nothing that can be found fault
with or blamed; the skilful reckoner uses no tallies; the skilful
closer needs no bolts or bars, while to open what he has shut will be
impossible; the skilful binder uses no strings or knots, while to
unloose what he has bound will be impossible. In the same way the
sage is always skilful at saving men, and so he does not cast away any
man; he is always skilful at saving things, and so he does not cast
away anything. This is called 'Hiding the light of his procedure.'

Therefore the man of skill is a master (to be looked up to) by him
who has not the skill; and he who has not the skill is the helper of
(the reputation of) him who has the skill. If the one did not honour
his master, and the other did not rejoice in his helper, an
(observer), though intelligent, might greatly err about them. This is
called 'The utmost degree of mystery."