Incidentally, Wu (Being-without-form) and You (Being-within-form) are two aspects contained in the Dao. The former can be regarded as a substitute related to the moment when Heaven and Earth were in chaos prior to their separation, while the latter can be regarded as a substitute related to the fundamental source of the myriad things. From Lao Zi's point of view, the world is oneness or unity, emerging from the movement of the Dao. In terms of the world's formation, the ancients believed that the separation of Heaven and Earth took place first, and the emergence of the myriad things came second; just as it was said: "There were Heaven and Earth, then the myriad things commenced to be" (see "Yizhuan Xugua" [Prelude of the Trigrams, A Commentary on the Yi Jing or The Book of Changes]). Therefore, Being-without-form and Being-within-form respectively stand for two stages in the engendering process of the world (see He Haokun & Huang Qiyue, Cong Dao De Erchongxing Kan Lao Zi Zhexue Tixi De Tedian [Looking into the Features of Lao Zi's Philosophical System from the Perspective of the Duality of the Dao]).
Being-without-form and Being-within-form operate as the dual character of the Dao, interrelated so closely as the two sides of a coin. Yet, these two aspects exemplify the dynamic course of the Dao moving from the invisible and universal to the visible and particular.
[6] The expression "Heaven and Earth" (tian di) is usually employed in Chinese to mean either nature or the universe as a whole.
[7] See [5] above.
[8] The Chinese word wan (ten thousand), when figuratively used, often means countless or innumerable, similar to "infinitely great or infinity" as a mathematical term. Therefore, "the ten thousand or myriad things" can be understood to mean "all things" or "everything."
[9] "Subtlety" is the English rendering of the Chinese term miao, which signifies, according to Wang Bi, "something extremely subtle." It is a fact that all things start with Being-without-form and then comes into Being-within-form, underlining subtlety as one of the Dao's major characteristics.
[10] I In Wang Bi's edition the word jiao is explained as "outcome." Literally it means "boundary." Some scholars extend this meaning to "clue" or "inkling." The Mawangdui silk copy of The Book of Lao Zi, the earliest edition so far discovered in China, uses another character pronounced jiao and meaning "shout," which seems obviously out of place in both the logical and contextual dimensions. It is possibly a mistake for another jiao which means "bright" or "clarity." Its extended meaning could be "show" or "manifestation," contextually corresponding to the preceding word, miao (subtlety). As has been observed, the Dao is delicate and subtle when it is functioning in its aspect of Being-without-form (Wu) as a potentiality, but clear and manifest when functioning in its aspect of Being-within-form (You) as an actuality (when it shows itself through the "myriad things").
[11] I Heshang Gong (fl. 179-159 B.C.) and Wang Bi punctuated the sentences in this way: Gu chang wu yu, yi guan qi miao; chang you yu, yi guan qi jiao (Therefore those constantly without desires, by this means will perceive the subtlety of the Dao; those constantly with desires, by this means will see the boundary of the Dao). This seems to interrupt the stream of thought of the chapter on the one hand, and does not agree with Lao Zi's persistent stance against desires of all kinds on the other. For he was convinced that desires as such are the primary cause of human conflicts and social problems, and often plunge people into restlessness and anxiety. Thus Lao Zi frequently advises people to reduce or abandon their desires as much as possible in order to preserve their spirits and lives in one sense, and in another sense to perceive the subtlety and manifestation of the Lao. Hence I prefer the punctuation originated by Wang Anshi. That is: Gu chang wu, yu yi guan qi miao; chang you, yu yi guan qi jiao, which is then rendered as "Therefore it is always from (the perspective of) the Being-without-form that the subtlety of the Dao can be contemplated; it is always from (the perspective of) the Being-within-form that the manifestation of the Dao can be perceived." The justifications for this can be found in the commentaries by many Chinese scholars today, such as Wang Huai, Yan Lingfeng, Chen Guying, Sha Shaohai, Gu Di, Zhou Ying, and others.
Some scholars (e.g. Gao Heng, Yi Shunding and Du Yushi) also adopt Wang Anshi's punctuation. Yet, they tend to paraphrase the sentences a bit differently by labeling chang wu (constant Being-without-form) and chang you (constant Beingwithin-form) as two interdependent concepts and facets integrated in the Dao. This viewpoint may well be taken for reference.

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