to Pope Adrian II., "Ipse Patrum monumenta _sequens renovavit_ et auxit."

What was the musical material on which he had to work, which he had to
put into shape, and to which he added new pieces? It is probably
substantially represented by the Ambrosian chant as we find it in the
oldest MSS. It seems most likely that it is the musical counterpart of
the primitive liturgy organized, as is supposed, about the epoch of Pope
Damasus, of which the Ambrosian, Gallican, Mozarabic, and Celtic are so
many variations, due to national characteristics. Documentary proof of
this is but scanty, but a study of the Lessons used at Mass supports the
theory as far as the text is concerned. It is further recorded that at
Monte Cassino the Ambrosian chant was fused with the Gregorian by order
of Pope Stephen IX. (1057-8). Here the Pre-Gregorian chant is simply
called Ambrosian.

ANTIPHON

[Illustration: Antiphon, Gregorian and Ambrosian]

Gregorian
O Sa-pi-en-ti-a, quae ex o-re Al-tis-sim-i
pro-di-is-ti at-tin-gens a fi-ne
us-que ad fi-nem, for-ti-ter su-a-vi-ter-que
dis-po-nens om-ni-a: ve-ni ad do-cen-dum nos
vi-am pru-den-ti-ae.

Ambrosian
O Sa-pi-en-ti-a, quae ex o-re Al-tis-sim-i
pro-ces-si-sti at-tin-gis a fi-ne
us-que ad fi-nem, for-ti-ter su-a-vi-ter
dis-po-nens que om-ni-a: ve-ni ad do-cen-dum nos
vi-am sci-en-ti-ae.

INTROIT

[Illustration: Introit, Gregorian and Ambrosian]

Gregorian
Gau-de-a-mus om-nes in Do-mi-no,
di-em fes-tum ce-le-bran-tes in ho-no-re
A-ga-thae mar-ty-ris: de cu-jus pas-si-o-ne
gau-dent an-ge-li, et col-lau-dant
Fi-li-um De-i.

Ambrosian
Lae-te-mur om-nes in Do-mi-no,
di-em fes-tum ce-le-bran-tes ob ho-no-rem
A-ga-thae mar-ty-ris: de cu-jus tro-phae-o
gau-dent an-ge-li, et col-lau-dant
Fi-li-um De-i.

GRADUAL

[Illustration: Gradual, Gregorian and Ambrosian]

[Illustration: Gradual, continued]

Gregorian
Ex Si-on spe-ci-es de-co-ris e-jus:
De-us ma-ni-fe-ste ve-ni-et.
V. Con-gre-ga-te il-li sanc-tos e-jus,
qui or-di-na-ve-runt
te-sta-men-tum e-jus
su-pe