Jōgon (浄厳:1639–1702) was a monk of the Shingon sect in the Edo period. In 1690 he authored the Shingon-shugyō-taiyōshō (真言修行大要鈔) as a summary of the training in Shingon esoteric Buddhism. In this work he emphasized that Ajikan Yoga (阿字観), a meditation consisting of the contemplation of the letter A (
), was the most important practice in Shingon. In particular, he argued that ‘all phenomena are originally unproduced’ (一切諸法本不生) is the true meaning of the letter A. And he stated that Honpushō (本不生) was a significant idea that indicated metaphysical existence without beginning or end. It is very important that he defined it as the meaning of Eternal Existence (本有). Furthermore, he argued that the content of enlightenment in Shingon Buddhism was superior to that of the Zen Buddhism which was thriving in Japan at the time. He insisted that the Shingon sect had advantages over other Mahāyāna Buddhist sects by clarifying the superiority of realizing Honpushō.
