佛祖統紀 47.12

47.12

述曰。唐明皇天寶中。度牒已用綾素　本朝太宗初年普度十七萬　真宗天禧普度二十三萬。應此時但用紙牒使之易辨。今既斥賣。欲重其價故用勅綾。比同品官之告身。亦見朝廷之重僧也。

The Commentary states: During the Tianbao era of Emperor Minghuang of the Tang, silk had already been used for ordination certificates. In the early years of Taizong of our dynasty, one hundred and seventy thousand were universally ordained; in the Tianxi era of Zhenzong, two hundred and thirty thousand were universally ordained. At those times, only paper certificates were used to make them easy to distribute. Now, since they are being sold off, in order to enhance their value, imperial silk is used, matching the patent of appointment of ranked officials; this also demonstrates the court's esteem for Buddhist monks.