A sequence found about the same date is called in old manuscripts

i

Also heilig ist der Tag

[30]Anon.

trans. by Catherine Winkworth, 1869

So holy is this day of days

No man can fill its meed of praise,

Since the Holy Son of God

Now hath conquered Death and Hell,

And bound the Devil who there doth dwell,

So hath the Lord delivered Christendom;

This was Christ Himself:

Kyrie Eleison!