Gyokuu - empty space

...Ichi-nen-gi holds that one can attain rebirth in the Pure Land by believing in Amida's original vow and chanting the Nembutsu once, while Tanen-gi holds that one must chant the Nembutsu as many times as possible until the moment of death in order to attain rebirth. The former was established by Gyoku and Kosei, while the latter was advocated by Ryukan. Ichi-nen-gi was followed in Kyoto and the Hokuriku region during Honen's lifetime, and placed emphasis on a single-minded faith (ketsujoyo), neglecting the practice of chanting the Nembutsu many times and eventually rejecting it....

*Some of the terminology explanations that mention "Gyoku" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…弥陀の本願を信じておこす，ひとたびの念仏で往生できるとするのが一念義，往生には臨終までできるだけ多くの念仏を唱える必要があるとするのが多念義。前者は行空，幸西らの立義，後者は隆寛の主唱にかかる。一念義は法然の在世中から京都･北陸方面で信奉され，一念の信心決定（けつじよう）に重きを置き，多念の念仏行を軽視し，やがて否定した。…

※「行空」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報