Thirty spokes converge upon a single hub;
it is in the hole in the center that
the use of the cart hinges.
Shape clay into a vessel;
it is the space within that makes it useful.
Carve fine doors and windows,
but the room is useful in it emptiness.
The usefulness of what is
depends on what is not.
First of all let me say that I love this verse. I love its simplicity and its powerful message.
Even as a child I had a connection with the meaning of this verse despite the fact that I had no idea the Tao existed. It’s funny, looking back I can remember noticing how the usefulness of a wall in my home was made more functional by the open space where a window or door was placed. Even then I understood that what is not (the opening in the wall) gave more meaning to what is (the wall).
Examples in our physical world
How useful would a sponge be if it were not for the hollow spaces contained within it?
How useful are the veins running through us if they are not hollow?
How useful is a guitar without the space in the body for the sound to reverberate throughout?
Without the empty space (what is not), these things are useless. There are many example of this concept in our physical world.
Metaphor for our minds
Of course this verse is not merely speaking of the physical structures around us. It is using these examples as a metaphor for our minds.
Our mind is like the sponge. If we are closed minded and fill every moment with the typical assault of constant thought, we miss out on the ideas and opportunities that are presented to us. Instead we are too busy listening to the constant barrage of thought.
If instead we open our minds and allow spaces to form between our thoughts, we allow new ideas, opportunities and paths to come to us. We become more connected to our true selves and therefore more content with our lives.
We can open our minds by being present in the current moment and notice what is happening now. We can allow spaces to form between our thoughts by meditating and learning to clear our minds from all of the chatter that most of us tend to fill our every moment with.
That is when the true usefulness of our mind and our lives can be fully recognized. Our mind becomes more useful when we realize that it is dependent on what is not.