I found this in " A Celtic Primer" by Brendan O`Malley:
O God of unchangeable power and eternal light,
look favourably on your Church, that wonderful and sacred mystery;
and by the tranquil operation of perpetual providence, carry out the work of the salvation of humankind;
and let the whole world feel and see that things which were cast down are being made new, and that all things are returning to perfection through Him from whom they took their origin, through our Lord Jesus Christ.
I thought it was wonderful.
Apparently it originally came from the Gelasian Sacramentary, about which I know very little, but I am sure Huw Raphael or SubDeacon Ben would know :-0
The Celtic Primer book comes with a floppy disk containing the whole text of the book itself in Word format, BTW, which I thought was rather neat.