Gaudeamus omnes in Domino, diem festum celebrantes sub honore Mariae Virginis: de cuius Assumptione gaudent Angeli, et collaudant Filium Dei.
“Let us all be joyful in the Lord, celebrating this festive day in honor of the Virgin Mary, whose assumption the angels enjoy, and they praise the Son of God.”
Click here to listen to an audio of the chant.
Sung by Liborius Lumma, Innsbruck (Austria).
Apart from its own Vigil Mass (not many feast days have such a Vigil Mass in the current Roman Catholic order), the Solemnity of Assumption has two introits to choose from. One of them (Signum magnum) is quite young and lacks medieval sources, so I will stick with the other one – and that makes my job easy: I already had a look at Gaudeamus some weeks ago, and Anthony Ruff too showed that this introit originally comes from the celebration of an other female Saint, Agatha.
Thus we find an introit that was not specially designed for this very day (except that the word Assumptione was included instead of festivitate or sollemnitate). Over the centuries it became sort of a “theme song” for Saint’s days, especially for the Mother of God.