大宋僧史略 1.19

1.19

Furthermore, that Jiangbiao takes the current eighth day of the fourth month as the Buddha's birthday follows the Ruiying jing. If the Zhou calendar were used, it would properly be the current eighth day of the second month; using the month with the dipper pointing to si makes it the sixth month under the Zhou calendar. Examining this, there are two reasons for the mistaken use of the month with the dipper pointing to si: first, hearing the sound and immediately using it without verifying the reality to ascertain the season; second, translators of sūtras mostly used the Xia calendar, and thus this error occurred. If it is as Nanshan said, sentient beings differ in what they see and hear, so the seasons are not uniform, and one should not rigidly adhere [to one]. Nevertheless, where the two lands connect and what the Tripiṭaka has transmitted, taking him to have been born in the time of King Zhao of the Zhou has the most reasonable basis.