Let me revisit the idea of beauty as holy sadness.
As I wrote below, beauty itself can't make us sad, because we can only be sad at an evil, and beauty is per se good. The "holy sadness" that people do, in fact, feel upon apprehending beauty is not caused by the beauty itself, but by the awareness this apprehension causes in them that there is beauty they cannot now apprehend.
In what sense, though, is the existence of beauty we can't apprehend an evil? In a comment, I repeated a formula from St. Thomas that evil is a privation of a good that is due, the lack of a good where a good ought to be. Does this mean that apprehension of beauty is "a right, or privilege, something that we are 'due'"?
Well... yes, I suppose it does. But it's something due us, not in the sense that things are due a person in justice, but in the sense that human nature is imperfect when that beauty is not present.
I'm hashing through this idea, and so making a hash of it, but to put it briefly: There are experiences of beauty that make us aware that we, as human beings, are capable of beauty, and that we ourselves are unfulfilled as long as that capacity for apprehending beauty is unfulfilled.
It's only through faith that we come to realize the full Beauty of which we are capable is nothing less than God. I don't think, though, that we need Christian faith to realize that other things in creation -- primarily other humans -- also fall short of their own capacity of being beautiful. Such a realization, which is also a cause of sorrow since it's a recognition of the absence of a good where a good ought to be, is a powerful natural spur toward a faith of beauty.
The various ways in which this natural capax pulchritudinis can be perverted are demonstrated in no subtle fashion in our culture. Still, my guess is that the natural capacity for beauty is less debased than the natural capability for truth -- in no small part because the capacity for beauty is barely recognized. If that's the case, then evangelization through beauty will, for many people, prove more fruitful than evangelization through truth.
In the end, it must all draw together, of course, because Beauty and Truth are One, but we time-bound creatures can only take each step in sequence.