The Mahayanist Buddhism of the Far East makes free use of such phrases as the Buddha in the heart, the Buddha mind and the Buddha nature. These seem to represent such Sanskrit terms as Buddhatva and Bodhicitta which can receive either an ethical or a metaphysical emphasis. The former line of thought is well shown in Santideva who treats Bodhicitta as the initial impulse and motive power of the religious life, combining intellectual illumination and unselfish devotion to the good of others. Thus regarded it is a guiding and stimulating principle somewhat analogous to the Holy Spirit in Christianity. But the Bodhicitta is also the essential quality of a Buddha (and the Holy Spirit too is a member of the Trinity) and in so far as a man has the Bodhicitta he is one with all Buddhas.
This conception is perhaps secondary in Buddhism but it is also as old as the Upanishads and only another form of the doctrine that the spirit in every man (antaryamin) is identical with the Supreme Spirit. It is developed in many works still popular in the Far East and was the fundamental thesis of Bodhidharma, the founder of the Zen school. But the practical character of the Chinese and Japanese has led them to attach more importance to the moral and intellectual side of this doctrine than to the metaphysical and pantheistic side.
[Footnote 100: E.g. in Mahaparinib. Sut. IV. 57, the Buddha says “There has been laid up by Cunda the smith (who had given him his last meal) a karma, redounding to length of life, to good fortune, to good fame, to the inheritance of heaven, and of sovereign power.”]