WuMing wrote:one further note: the approach to awakening of the stages prior to the tenth stage in Kūkai's model is only vertical and a causal one (inbun 因分). This changes completely in the tenth stage, which is horizontal and a resultant one (kabun 果分) in which any distinction between exoteric and esoteric is dissolved; and here again the capacity of the practitioner comes into play. So, the view is entirely different in the realization of the tenth stage, than the view in the stages prior to the tenth stage. While one is cruising through the different stages or dwelling in a particular stage, it can be said that there is a necessity of time required to practice, but from the point of view of the tenth stage, there is no time required.
This I thought was made quite clear in
The Precious Key to the Secret Treasury as previously quoted (sadly it seems Dharmawheel does not allow me to go back and correct my lack of citations). Expanded here to capture further relevant context.
Each of these vehicles may appropriate the name "Buddha" for its own vehicle, but when viewed in light of the subsequent vehicles, it becomes a frivolous assertion. None of the previous stages of the mind is stationary, and therefore they are described as having no own-nature; none of the subsequent stages of the mind is the ultimate fruit and therefore they are all causes. When viewed successively in relation to each other, each is profound and wonderous, and therefore they become "progressively deeper and progressively more wonderous."
The Precious Key to the Secret Treasury as translated by Rolf Giebel; see Shingon Texts
However, at least in
The Precious Key, Kūkai does not expound on what precisely these stages of the mind are causes of. If we consider that a śrāvaka, a bodhisattva, or a Buddha has awoken to a state from which there is no return to that of a deluded being, then it stands to reason that the only progression possible from that point is up. If that progression is possible, then it would seem to me that these states of mind would be causes for the peeling away of dual concepts, ultimately causing the being to progress to the next higher state of mind.
There is a careful distinction here though, because the tenth stage of the mind is the ultimate and presumably perfect non-dual identity with Mahāvairocana. How then could the ninth stage be the cause of the tenth stage? Rather, it would seem that it is the elimination of the barriers preventing the being from such a realization that the stages of the mind would be the cause of.
In light of this, it makes perfect sense to me that Kūkai would assert in
The Secret Key to the Heart Sutra that
The fifth, bodhi svāhā, explains the ultimate realization of each of the foregoing approaches.
The Secret Key to the Heart Sutra; Kūkai: Major Works
How else could we suggest that the path of the śrāvakas, boddhisattvas, and the miriad of Buddhas have the same ultimate realization unless they all ultimately lead to the perfect non-dual identity with the Dharmakaya? Time is, of course, ultimately a non-issue when taken in context of the originally unborn.
But more to the original point of the thread, all of this seems to indicate that Kūkai did not present the Shingon teachings as distinctly superior to other teachings. Rather, he seems to present the Shingon teachings as the ultimate destination that all cultivators are heading towards. This seems to stand in stark contrast to some of the liturature of other schools of Buddhism who always seem to be vying for dominance of some form or another. I find this to be fascinating and appears to be another piece of evidence to support Abe's assertion in
The Weaving of Mantra that the success of Shingon had more to do with Kūkai's ability to integrate Shingon with the teachings of other schools than it did with the idea that he pushed Shingon as a clearly superior and distinct teaching.