The essence of things in the Dao

Thirty spokes converge at the hub of a wheel,

but it is the emptiness at the center that allows the wheel to function.

Clay is molded into vessels,

but it is the hollow space within that makes them useful.

Doors and windows are carved to create a house,

but it is the empty room within that gives the house purpose.

Thus, "physical forms" provide practical benefits,

while "emptiness" holds the true essence of utility.

(This passage uses three metaphors—the wheel, pottery, and architecture—to illustrate the dialectical relationship between "presence" (being) and "absence" (non-being). While tangible materials ("presence") form the foundation, it is the seemingly "empty" spaces ("absence") that create functional value. The two complement each other, working in tandem to fulfill an object's complete purpose.)