The Nirvana Sutra was the last lesson taught by Sakyamuni just before his death; and it was this lesson that Rencho had accepted as part of the “Treasured Gem” which he had received through his vow to Akasagarbha (Kokuzo Bosatsu), the Bodhisattva of Wisdom. The four principles of learning which the sutra established were:

• Rely on the law (The Dharma), and not on any person;
• Follow only the teachings of that sutra which is regarded as complete and final;
• Follow meanings, not words;
• Follow wisdom, not biased thinking.

With these guidelines strong in his mind, Rencho began the final steps of his studies in fulfillment of the vow he had made to Akasagarbha. He would read every Buddhist text ever brought to Japan, the writings of every saint, and the commentaries of every great thinker; he would master the teachings of all ten Japanese Buddhist Sects; he would draw the truth from them in order to discover the true meaning of Buddhism and the one Sutra which revealed that meaning.