Subduing guest-dust afflictions is like letting muddy water settle.

When we sit in Chan, we have to cleanse our mind and reduce our desires. This is the first step in cultivation. Cleansing the mind refers to subduing afflictions, which are transient, like a guest who does not stay, like particles of dust that fly about.

Our turbid afflictions make us like a jar of muddy water. If we keep shaking the jar, the water will remain murky and we will not be able to see the bottom of the jar clearly. But if, after we pour the muddy water into a jar, we do not disturb the jar, then the mud and silt will settle to the bottom. This is the first step in subduing guest-dust afflictions. Sitting properly in meditation for even one ksana (a moment) generates more merit than building as many pagodas of the seven jewels as there are sand grains in the Ganges River. That is because by sitting in meditation, we can subdue our guest-dust afflictions and allow the silt of the five desires to settle down.

A clear mind is as a still pool
that can reflect the moon.
A calm will is as a bright sky
without a trace of clouds.