Appendix
The Trisagion, or Cherubic Hymn, has been in use in the worship of the Eastern Church from the very earliest. No form of adoration is of such frequent occurrence in all the offices of the Church. Originally the Trisagion (Thrice Holy), was in the exact form found in Isaiah iv. 3, but as the years passed, additions were made to it to express doctrine both orthodox and heterodox. The accompanying form is the one found in the service books, and is in common use at the present time.