Laozi wrote in the Tao Te Ching that the Tao which can be told is not the eternal Tao. And that it exists before Heaven and Earth. With the fall from Tao, Te (virtues) became valued.
Confucius lamented that people love beauty more than virtues.
A few hundred years later, Mencius indicated that humans (baby) are born good.
All three sages knew the Book of Changes (the Zhouyi/ the Yi) well.
The ancient sages and the wise down the ages all point to Heaven and Earth. Those who fully grasped their esoteric meanings reached the Center (Zhong) where heaven and earth, the eight trigrams and the myriad things, is said to exist.
To assist fellow travelers of the Way, they tried to make it easy and simple. They even assign symmetric things like the round and the square to heaven and earth. But still many down the ages seems to stumble and founder.
It is not that easy and simple after all to travel the magical far journey of the Way. No ancients said it was so anyway! Otherwise they would have no cause to lament.
Instead of following the second class scholars who invariably point to the sky and the ground (Chinese pun intended) by trying to fool students and experts alike with their lengthy essays and rhetoric, one would try to make it simpler and easier for deep thinkers and fellow students who cultivate Tao.
If you cannot fully understand why the ancients point to Heaven and Earth, why Qian and Kun represent the Light and the Dark, the easy and the simple, the round and the square, and the combination of both equates the Center; then you probably would not know why earnest and sincere followers of the Way need the dual cultivation of essence and life to return to Tao.
If you are already on the path or a deep thinker in ancient Chinese philosophy, try to make sense of why I say this:
‘Inside out, outside in’
It could be easier and simpler or more explicit than trying to understand what the real masters said, let alone the ancients and the holy sages, to ‘Square the circle, round the square’.
If you understand both indications and know how to cultivate that, then perhaps you could be truly on the Way!
But how would I know?