"The emptier the cart, the more noise it makes."

“Once, a long time ago, I was walking with my father when at a bend he suddenly stopped. After a moment of silence, he asked me:
– Besides the chirping of birds, do you hear anything else?
I sharpened my hearing and, after a few seconds, answered.
- I hear the noise of a cart...
- Right, said my father.
It's an empty cart.
I asked him:
– How do you know it's an empty cart if we can't see it yet?
And he answered me:
- It's very easy to tell when a cart is empty, it's because of the noise.
The emptier it is, the louder it hums and makes more noise.
Today, as an adult, when I see a person who talks a lot, interrupts other people's conversations, proves himself to be inappropriate, brags about what he has, feels powerful and despises those around him, it still seems to me that I still hear my father's voice saying:
"The emptier the cart, the more noise it makes."