Listen to the Introit for the first Sunday of Lent:
Lent – First Sunday: Introit from Corpus Christi Watershed on Vimeo.
That’s mode 8, which might be regarded as the lightest and most elevated, the most song-like, of all the modes. That chant is anything but dreary.
It’s not a fluke. Look at the Offertory chant for same day. It’s mode 8 too:
Lent – First Sunday: Offertory from Corpus Christi Watershed on Vimeo.
Now, if you are using hymns instead of Gregorian propers, there’s a good chance that you will be choosing music that might be seen as rather more depressing, such as “Forty Days and Forty Nights.”
What’s all this about? Perhaps the Gregorian tradition is reminding here that while Lent is a penitential season, Sunday does in fact remain a feast day – a real break in the fast. It is a mistake to try to cram the whole of the Lenten spirit into the Sunday Mass.