Chapter 40 of the Tao Te Ching

That is to say: As soon as beings return to non-being, the Tao gives them (again) the vital movement.

河上公 Héshàng Gōng : The word 反 fǎn wants to mean 反于无 fǎn yú wú « return to non-being ».

E: The movement of the Tao, that is to say the impulse that the Tao gives to beings, has for root, for origin, their return (to non-being). If they were not returning to non-being, (the Tao) could not put them in movement. It is necessary that they condense, that they tighten (that they decrease), to be able to reach then all the fullness of their development. This is why the return to non-being allows the Tao to put beings in movement, that is, to make them be reborn.

B: Among all beings in the universe, there is not a single one that does not need to return to non-being to exist again. It is only when they have returned to an absolute rest, that the Tao puts them again in movement and brings them back to life. Thus the rest is the basis and the principle of the movement.

Literally: « 弱 ruò, the weakness of the Tao, is its use ». A explains the words 道之用 dào zhī yòng by 道恒用之 dào héng yòng zhī, that is: « (The weakness is) what the Tao constantly uses ». This is why it can subsist eternally. E has adopted the same sense: Weakness is the constant state of the Tao; if it was not weak, it could not subsist long.

Other commentators have understood that the weakness was the means to make use of the Tao, that is to say, to observe, to imitate the Tao. B: If those who cultivate the Tao knew that the return to the emptiness, to the rest, is the basis, the principle of the movement, they would weaken their will, they would make their heart empty. As soon as the will is weakened, the heart becomes empty; when this emptiness is pushed to its limit, one enters into a perfect quietness and one returns to one's root. Here is the most powerful means of renewing one's nature.

河上公 Héshàng Gōng : By the weakness one resembles in some way the Tao. 张默 Zhāng Mò : Having the heart empty and tranquil internally, being soft and weak externally, this is the means of returning to one's root (to the Tao). 李息斋 Lǐ Xīzhāi : By developing, the beings become strong. If one returns from the strength to the weakness, one will be able to arrive little by little to the Tao.

A: The ten thousand things are born of the sky and of the earth, which have a determined place in the universe. This is why 老子 Lǎozǐ says: « They are born of the being ».

B: Where do the sky and the earth come from? They are born of the non-being (of the Tao). The Tao has no form, which is why 老子 Lǎozǐ says: « the being is born of the non-being ».