The Division of External Appearances Necessarily Includes External Dharma-Dhātus

If the external appearance aspect contained only the five dusts without the dharma dust, then the images entering the eye would lack reflections. The distinction between upright and inverted reflections constitutes the dharma dust, which pertains to form characteristics. Without the dharma dust in the external appearance aspect, what enters the eye would be merely a mass of color—devoid of shape, posture, or distinctions in quality and texture. Anyone can observe what the images in others' eyes look like to understand this.

For example, when looking into a mirror, the appearance outside the mirror represents the external appearance aspect. The mirror captures the reflection of this external appearance aspect, and the image formed on its surface is called the internal appearance aspect. Without the external appearance, there would be no image on the mirror—this is the factual reality.

Generally, the image on the mirror closely resembles the external appearance: whatever exists outside is reflected on the mirror, and whatever form the external appearance takes is mirrored identically. Since the internal appearance aspect contains dharma dust, how could the external appearance lack it? The Tathāgatagarbha manifests appearances truthfully—"truthfully" meaning identical to the external reality. The form characteristics, apparent characteristics, and non-apparent characteristics of the external dharma dust are all revealed through the mirror, matching the external appearance exactly. Whether through direct observations in meditative concentration or logical reasoning, the conclusion remains consistent.