you should say more. about the gregorian chants
OKAY!
So. Gregorian chants are, historically speaking, incredibly significant, as they're one of the first kinds of music to be recorded on paper in notation in Church history. A lot of modern church people really liked them in the 90s because, along with a very successful marketing campaign by the particular monks responsible for the album in the original post, they saw it as an opportunity to bring sacred rhythms back into everyday life. An awful lot of Church tradition is about being connected with the past, and the rest of it is about looking to the future, so having this tradition from the past brought into the present was likely a big selling factor.
In addition, New Age spirituality got ahold of Gregorian Chant when this album came out. No matter if you were part of the Church or even any church at all, the unique qualities of Gregorian chant (in marked contrast to pop and rock music of the day) lent themselves to meditation, and the aforementioned rhythms of the day likely also appealed to at least some of the non-Christian listeners. I don't know a lot about modern spirituality or even New Age spirituality, so if someone wants to add to this post I'd love to see it.
Now we get to the really neat part, the part that I'm actually good at and can definitively say something about. This is the part that's full of jargon (or it should be), and I'll do my best to define it all for you.
Gregorian chant, as you can find on Wikipedia, is a part of an only slightly larger category called "Western plainchant". Western in this context refers to Europe, specifically Western Europe (the area around modern England, France, Germany, and to some extent Italy). Plainchant is a kind of monophonic (with only one melodic line and no harmony or accompaniment) music that was sacred, which means that this style was never used in the secular music of the day.
Gregorian chant comes in one of three "levels of complexity" so to speak, and in one of two "styles" (this is the wrong word but I can't think of the right one right now). The levels of complexity are: 1. Syllabic. The entire chant is made up of single syllables on individual notes, with rare or no instances of movement between notes on the same syllable. The melody could move, but it would not (as a general rule) have more than one note on any given syllable. 2. Neumatic. Most of the chant is made up of single syllables stretched out between 2-4 notes, with rare or no instances of movement between notes on the same syllable lasting for more or less notes than this. 3. Mellismatic. Most of the chant is made up of single syllables stretched out between more than 4 notes, up to a single syllable being used for an entire piece (later in the period, once people started to get freaky with it). I honestly don't remember very much about the styles but here you go @effemimaniac knowledge for you!











