XVIII. What are the Three Realms

The Three Realms are: the objective realm, the realm with substance, and the exclusive mental realm. These are all the phenomenal objects corresponding to the seven consciousnesses. Beyond these, there is also the fundamental realm, which does not correspond to the seven consciousnesses.

The objective realm is the manifest form or manifest object corresponding to the five consciousnesses. The realm with substance is the phenomenal object corresponding to the seventh consciousness and the simultaneously arising mental consciousness. The exclusive mental realm is the phenomenal object corresponding to the independently functioning mental consciousness. Both the objective realm and the realm with substance are phenomenal objects transmitted from the fundamental realm into the superior sense faculties.

"Substance" may also be called the particles of the four great elements. Matter containing these particles is referred to as the fundamental realm and the realm with substance. The fundamental realm undergoes transformation from the very beginning of transmission, changing into a phenomenal object perceptible by the seventh consciousness. When it enters the five sense faculties and the superior sense faculties, it is altered again. Continuously changing throughout the transmission process, it ultimately becomes the objective realm and the realm with substance. For example, a flower is the fundamental realm. When reflected by the first mirror, this flower becomes an image in the mirror, resembling the flower in the fundamental realm yet differing in substance. When another mirror reflects the flower in the first mirror, the mirror produces yet another image of that flower. This image differs from the previous two, though sharing some similarities, yet it becomes more illusory and less substantial, having undergone further alteration. Thus, when ten mirrors reflect one another successively, what ultimately appears in the final image? The phenomena of the five aggregates and the six dusts in the worldly realm are precisely like this.