阿彌陀經疏 1.32

1.32

'At one time' means that this teaching of the Pure Land was heard by me on such-and-such a year, month, and day; yet it does not mention the year and so forth, but merely says 'at one time', because the royal calendars and temporal systems of various lands were each different. For example, this land has four seasons, while that land has three periods; the Eastern Xia (China) takes the conjunction of the sun and moon (new moon) as the first day of the month, while Western India takes the full moon as the first day of the month. If it is already like this between these two regions, what of the four barbarian lands? Since it is difficult to determine uniformly, it universally says 'at one time'.