But if you imagine in me some special knowledge of the path to birth other than the nembutsu or of scriptural writings that teach it, you are greatly mistaken. (Tannisho 2; CWS, p. 662)
Yuien, the author of the Tannisho, mentions the scriptures, which Shinran especially cherished, towards the end of his book:
You must under no circumstances misread the sacred writings. I have selected several important authoritative passages and appended them to this volume as a standard. (Tannisho, Postscript; CWS, p, 679)
The scriptures that Yuien is referring to here are short texts written by Seikaku and Ryukan, who were fellow disciples, with Shinran, of Honen Shonin. While Honen made it clear in the eighth chapter of his principal treatise (A Collection of Passages on the Nembutsu Chosen in the Original Vow) that it is through faith that a person of nembutsu can enter nirvana, some of his disciples lost sight of this vital fact. In order to try to assure themselves of birth in the Pure Land, they became mired in the idea that it was the quantity, rather than the quality (faith) of nembutsu, that would lead to birth.
Shinran was of the same mind as Seikaku and Ryukan and taught the absolute necessity of faith. Two of these scriptures, which are the authoritative texts that support the orthodox Pure Land teaching outlined in the Tannisho, are familiar to us through Shinran’s commentaries on them. They are Essentials on Faith Alone by Seikaku and The Clarification of Once-calling and Many-calling by Ryukan. Shinran’s commentaries on these precious writings can be found in The Collected Works of Shinran, Volume I, pages 451-490. These, as Yiuen says, are ‘the standards’ of the teaching.
Of course, the Sutras and the writings of the seven Dharma Masters are essential resources, but they are not as succinct as the texts that Yuien commends to us. It was actually the scriptures written by Seikaku and Ryukan that Shinran repeatedly read and copied for his disciples. In addition, he wrote the Hymns to give ready access to the essential contents of the Sutras and the teachings of the Dharma Masters. Once he moved back to Kyoto in about 1234 it also became necessary to teach by way of his correspondence. These letters are also wonderful resources and lay before us a proper understanding of the nembutsu teaching and way of life.
We may wonder why a scholar of Shinran’s depth and breadth was so focussed of these short treatises. After all, he spent twenty years as a monk dedicated to studying and practicing the Dharma on Mt Hiei. We learn from his wife, Eshinni, that Shinran knew the Larger Sutra by heart. If we read his major work The True Teaching, Practice, and Realisation we uncover a goldmine of wonderful, and often extensive, quotations from many Sutras and treatises.
But the short scriptures of Seikaku and Ryukan, along with the Tannisho itself, are as important as they are because they are the culmination and the epitome of the scriptural sources through the ages:
All the sacred writings that clarify the significance of the truth and reality of Other Power state that one who entrusts oneself to the Primal Vow and says the nembutsu attains Buddhahood. (Tannisho 12, CWS, p. 668)