What you have written in inquiry is truly to the point. The Garland Sutra states that those who have attained true shinjin are already certain to become Buddhas and therefore are equal to the Tathagatas. Although Maitreya has not yet attained Buddhahood, it is certain that he will, so he is already known as Maitreya Buddha. In this manner, the person who has attained true shinjin is taught to be equal to Tathagatas.
Jyoshin-bo’s statement that this person is equal to Maitreya is not in itself wrong. I sense that he has not attained a deep understanding, though, when he criticizes as self-power the view that that mind rejoicing in the attainment of shinjin through Other Power is equal to Tathagatas. Please reflect on this very carefully.
To think in self-power that one is equal to the Tathagatas is a great error. But it is because of the shinjin of Other Power that you rejoice; how can self-power enter into it? Please consider this fully.
I have spoken of this matter in detail to the bearers of this letter. I would be well for Jyoshin-bo to ask them about it.
Tenth month, 21st day
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