There was something formless and perfect
before the universe was born.
It is serene. Empty.
Infinite. Eternally present.
It is the Mother of the universe.
For lack of a better name,
I call it the Tao.
I call it great.
Great is boundless;
boundless is eternally flowing;
ever flowing, it is constantly returning.
Therefore, the Way is great,
heaven is great,
earth is great,
people are great.
Thus, to know humanity,
To know earth,
To know heaven,
understand the Way.
To know the Way,
understand the great within yourself.
Think of all the wondrous things around you. The glory of the morning sunrise. The instinct that drives animals to know their purpose without anyone to direct them. The ability for a human life to form even though the number of factors that need to be in place to form that life is staggering. The myriad of incredible and unexplainable things that surround you.
In order to understand anything, all you need to do is look within yourself. The greatness that is in everything is also in you.
That is exactly what this verse is referring to. It is saying that before you can understand anything (I.e. the earth, heaven, the Way), you must first understand the greatness within yourself. For that greatness is the “Mother of the universe”.