There are many such categories, but they are all different ways to express the same thing ─ emptiness. Self-nature is empty. Your self-nature is the emptiness of self-nature.

The mind is a sence organ; dharmas are its object.
The two are like marks on a mirror.
Once the dust is rubbed off, the light begins to appear.
When both mind and dharmas are forgotten, this is true nature.


In this stanza, Yung-chia is talking about the process of practice. The mind does not move on its own. The mind moves because it comes into contact with external phenomena. Phenomena can be broken down into two categories: mental dharmas ─ those within the mind; and material dharmas ─ objects with form and shape. The mind interacts with external, material dharmas through the sense organs. The motion of mind is, in itself, a mental dharma, but here the poem is discussing external dharmas, or form.

External dharmas are sometimes called sense objects. Actually, the literal translation of the Chinese term is "sense dust." Once the mind perceives external dharmas, a series of mental dharmas ─ which are sense objects of the sixth consciousness ─ is triggered. Mental dharmas by themselves can also trigger other mental dharmas. Any mental activity or external phenomenon that influences the mind can be considered sense dust. It is this sense dust which accumulates and conceals the mind mirror.