宋高僧傳 18.32

18.32

系曰：蔡邕是張衡後身，智威本徐陵前事，驗皆昭晰，理且弗虛。至於聖人功用自在，此亡彼出，利見無方。僧會捐世既遐，唐來化越，立逝屹然，異中之異。苟非應物現形，如水中月，孰能預於是乎？

The appraisal says: Cai Yong was the rebirth of Zhang Heng; Zhiwei was originally the former life of Xu Ling. The proofs are all evident, and the principle is not hollow. As for the free and unhindered functioning of holy sages, disappearing here and appearing there, their beneficial appearances have no fixed direction. Seng Hui had left the world long ago, yet during the Tang he came to transform the region of Yue, passing away while standing erect—a wonder among wonders. If not for manifesting forms in response to beings, like the moon in the water, who could partake in such an affair?