Our mind is analogous to a cup of muddy water. The longer you keep a cup of muddy water still, the more the mud settles down and the water will be seen clearly.
The quote illustrates how our mind can be compared to a cup of muddy water. When the water is disturbed, it remains unclear due to the mud swirling around. This serves as a metaphor for our thoughts and emotions, which can cloud our mental clarity when we are in a state of chaos or agitation.