The Guan wuliangshou jing， the Sutra of the Meditation on the Buddha of Immeasurable Life， given the reconstructed Sanskrit title of Amita^yur-dhya^na-su^tra; 1 fasc.， translated in 424 by Ka^laya/sas 畺良耶舍， believed to be of Central Asian origin. T 365.12.340c-346b. The catalog name is 佛说观无量寿佛经， and it is also known as the 无量寿佛经， 无量寿佛观经， 无量寿观经， 十六观经， and abbreviated as 观经. There was reportedly one other translation， but it had been lost since 730. This is one of the three principal scriptures三部经 of the Pure Land school 净土宗. It is recorded as being a sermon delivered by S/a^kyamuni at the request of the Queen Vaidehi^ 韦提希 of Magadha， while her husband was imprisoned. This scripture teaches sixteen kinds of meditation 十六观 as a means for attaining rebirth in the Pure Land. It concludes by saying that even the most sinful of people can attain this kind of rebirth by chanting the name of Amita^bha Buddha 阿弥陀佛. This text was commented on profusely in East Asian Buddhism， the most important early commentary being that of Shandao 观无量寿佛经疏， with others by Huiyuan 观无量寿经义疏， Zhiyi 观无量寿佛经疏， and Jizang 观无量寿经义疏. It served as a fundamental teaching text for all later Pure Land master， including Tanluan， Daocho， and Ho^nen 法然. Important modern research was done on the text by Takakusu Junjiro， who translated it with the Sanskrit title given above （1894）.