Yogicfire wrote:I have been reading about the amala-vijnana (the ninth consciousness). Up until recently, I thought that the mind only school had eight consciousnesses, and that the alaya-vijnana was the base consciousness. However, some of the Far Eastern schools appear to have added a ninth consciousness, amala-vijnana, the pure consciousness.
As I have seen it is not a "ninth consciousness", as if it is in addition to the common eight.
Rather, it is the term used for the eighth consciousness in the stage of a Tathagata, which corresponds to the Great Mirror Wisdom, which is the result of the transmutation of the alaya-vijnana (per Ven. Xuanzang's
Chengweishilun).
I would be interested in hearing any thoughts on this doctrinal development, and some explanation on the exact correspondence between the alaya-vijnana and the amala-vijnana. Why was there a need to introduce this extra consciousness?
If understood in the above sense, it is not actually an extra consciousnes.
The excerpt from
Chengweishilun: Chapter 3, Section 20. "Names and Types of Eighth Consciousness";
".... Finally, it is called the 'immaculate consciousness' [amala-vijnana], which is extremely pure, because it is the support for all unsoiled dharmas. This name only applies to consciousness in the stage of a Tathagata, because among bodhisattvas, [saints of] the two vehicles, and ordinary people, consciousness holds seeds and can be perfumed, and these people have not yet acquired an eighth consciousness that is purified, etc.. As a scripture says, 'The immaculate consciousness of a Tathagata is the realm of purity and nondefilement, free of obstacles, and corresponding to perfect mirror knowledge.'" 
nopalabhyate...