It's just one of those records. I've had it for a few years and I never stopped listening to it. It's just good for you.
"This Mortal Coil" was a band made up of artists from other 4AD bands (Dead Can Dance, Wolfgang Press, Cocteau Twins, Colourbox, Breathless, Dif Juz), so it was like (well, not like, really) a dream band. When all the ingredients are great, the result is this.