Why can the eighth consciousness discern all dharmas?

Because all dharmas issue forth from the mind of the eighth consciousness, the slightest arising, transformation, and cessation of all dharmas is governed by the eighth consciousness, sustained by the eighth consciousness, and inseparably bound to it—not apart for even an instant. The eighth consciousness itself also possesses the nature of discernment, the capacity to know, and mental factors (caittas); therefore the eighth consciousness can discern all dharmas, can know all dharmas, and can govern and determine all dharmas. In essence, all dharmas are parts of the eighth consciousness, are things within the mind of the eighth consciousness, are transformed manifestations of the eighth consciousness; thus all marks are the marks of the eighth consciousness, without any difference—the whole is the single true dharma-realm of the eighth consciousness.

Including the five consciousnesses, the mind consciousness, and the manas—all are marks of the eighth consciousness, stand-ins for the eighth consciousness, governed by the eighth consciousness. Therefore the eighth consciousness, from beginning to end, can likewise truly and as-it-is discern these seven consciousnesses, knows the mental activities and modes of operation of these seven consciousnesses, and can determine the arising, abiding, changing, and ceasing of the seven consciousnesses. All dharmas are articles made of true gold; their nature is all the nature of true gold. The quality of the true gold determines the value of the gold articles; whoever has mastered the true gold has mastered all the articles. A single maṇi jewel radiates throughout the great thousand worlds, its light shining in all directions.