Tao may have many aspects in its interpretation. For our discussion here, Tao represents the proper order in nature. We may recognize this order as the proper relationship between the myriad things. We may also envision that we “identify” the myriad things according to this order. In the latter case, Tao becomes the ontological source of the myriad things, and the myriad things are “born” from Tao, as described by Lao-tzu. Therefore, the myriad things should reflect the order of Tao in nature. We can search for the principle of this order by observing the proper order of the myriad things.
In other words, our mind should carefully perceive the order of the myriad things in nature according to this principle of Tao. We can then describe this principle as seen in the phenomenal world, as Lao-tzu has done in the Tao Te Ching. When we describe Tao, we are always describing the principle of Tao. Tao itself is beyond our description.
This principle of Tao is summarized by Lao-tzu in Chapter 1. Lao-tzu first chooses Wu and Yu as an example of two opposites to characterize two simplistic orders of the myriad things.  The myriad things seem to be the same or different, so Wu and Yu are two distinct names that we are already familiar with, and we can use them as the starting points for our discussion of the actual order of the myriad things.
In Verse 2, Lao-tzu specifically associates Wu and Yu with the order in the myriad things. He identifies them as the two possible orders. He associates Wu with the “origin of the myriad things,” where the myriad things are not yet born. In Wu, the myriad things are without “differentiation.” He associates Yu with the “mother of the myriad things,” where the myriad things are already born; and are “differentiated.”
That is, we can view the myriad things to be in either of the two states: They are either completely the undifferentiated or they are totally differentiated. This is a conventional dualistic view of the nature of the myriad things. We often wonder between these states of the myriad things.
However, Lao-tzu knows that such oversimplified or the first-order description cannot show the true relationship of the myriad things. The truth is that they are in some way the same and, at the same time, are in some other way different. In Verse 3, he starts to discuss the true relations as Heng Wu and Heng Yu.
Formally, we shall retain the word Heng in our discussion. We may interpret Heng as True and use True Wu and True Yu to show the true order of the myriad things. The logic of Tao philosophy is the logic of using names (Wu and Yu) to describe True Names (Heng Wu and Heng Yu).
In the following, we shall analyze each verse in Chapter 1 in more details. This will be our formal presentation of the principle of Tao and its key concepts.
 Chapter 55: Born with Tao and preserved with Te, formed as things and completed as vessels. 道生之而德畜之，物形之而器成之。 There are two levels in the phenomenal world: Forms (形) and Objects (器) as used in our systematic model.
 This Chapter describes the principle of Tao philosophy. To show this principle, we may take Wu and Yu to be any two opposites and arrive at the same conclusion of the logic structure. We choose Wu and Yu as the states of the myriad things, based on the interpretation of Verse 2 of Chapter 1.
 We may use the following example as an illustration. Before a mother gives birth to two offspring, the two offspring may be considered as “undifferentiated (Wu).” After birth, the offspring are “differentiated (Yu).”