James Joyce, as extrapolated by Joseph Campbell, said that the function of improper art is to bring the perceiver to a state of desire (which makes it pornographic - whether the content is sexual or not) or to elicit fear and loathing (which makes it didactic). Proper art, on the other hand, brings the perceiver to a state of aesthetic arrest. It stops you in your tracks. It takes you out of your regular, limited mode of perception allows you to see the infinite in the everyday, the divine spark in everything.
Proper art also makes you shut up and pay attention, without even seeming to try.
Dead Can Dance has a full sound, a number of musicians playing diverse instruments to create a soundscape that suggests different countries, time periods, even different planets. And yet in this performance, there's just her, singing. Slowly. With power, and grace. And focus and concentration. All of which transmits to the audience, who watch and listen in a silence that acknowledges the sacredness of the performance, of the moment, and by extension, of everything. It's literally impossible for me to imagine her singing this song without having that same effect on any audience, anywhere. Children at the circus, frat boys in a strip bar, Hell's Angels around the bonfire, aloof hipsters in a vegetarian restaurant you've never heard of, women climbing out of a limo three hours into a stagette - all would forget themselves for a few moments, and listen to the truth, enraptured.
It's a traditional song, and a familiar melody to anyone who's spent any time listening to Irish folk music. But it's entirely hers, in the authority she brings to it.
If ever the goddess Athena manifested herself on earth, this is what she'd sound like.