Thus the whole realm of existence is nothing but a stage of “mutual participation” of beings and their conditions, a grand harmony of all possible instruments glorifying in unison the fundamental oneness of existence.
In the light of this world-view, the ideal aim of Buddhist perfection consists in the full realization, on the part of every one, of the Buddha-nature, or in the participation of our life in Buddha’s purpose and work. For Buddha-nature is universally and primordially inherent even in existences of the utmost viciousness, and all of them can be elevated to Buddhahood. Indeed, mankind stands midway between Buddha, the Supreme Enlightened, and the most degraded infernal being, and, therefore, has the possibility of advancing further on the way to Buddhahood or of descending to the beasts or to the nethermost purgatories or hells. Hence the task of man consists in comprehending the truth of the all-pervading Buddha-nature and of mutual participation working throughout the realms of existence, especially the truth of the interaction and interdependence of different beings and their qualities, functions, and so on.
History of Japanese Religion