Technically, a certain Amida Buddha might not have existed long ago as he only exists in the Buddha world Sukhavativyuha, hence called the Pure Land of Bliss.
All of the possible Pure Lands do not exist in material space-time as they are of a Buddhist metaphysical nature.
Indeed, it may become necessary to believe in the Pure Land and in Amida Buddha in order to implement Nembutsu practice faithfully, as belief in the Pure Land is based on what is called the Primal Vow, which might place them next to God and unicorns.
This is similar to the stigma of mental illness where "it's all in your head." If God and unicorns are made up and due to the wildness of one's imagination, then the same thing might be said of Amida Buddha.
However, this is like comparing apples to imaginary oranges. The apple of this world may exist, but imaginary oranges only exist in the mind. Even though you cannot taste the oranges, you can still have a mind's view of them.
Likewise, the mind's view of Amida Buddha and the Pure Land is but a metaphysical reality.
Belief in the Pure Land is based on faith in the Primal Vow and especially rebirth in the Pure Land.
While there has never been any proof that the Pure Land exists except as metaphysical reality, a Buddhist would have to suspend disbelief, believe in what the three Pure Land Sutras say about Amida, and — as a result of his studies — have faith in the Primal Vow.
Indeed, I sometimes try to transcend my imagination when chanting Nembutsu quietly. For I believe in what the three Pure Land Sutras says about Amida Buddha and the Pure Land of Bliss.
That is what metaphysics is about: transcending the physics of this reality for the higher goal of happiness and peace for all sentient being in the Six Realms of Desire!
For information on the Primal Vow and other Buddhist terms in this article, check the tags below.
Original post: June 24, 2013 1242H PDT
