Here's a clean version and sort of summary of what I would say:
Line 1 - It is not an ordinary horizon, but an endless one--one like you have never experienced, or have even imagined. Horizon here symbolizes something terribly beautiful, wide open, and awe-inspiring, but at the same time something that makes you feel utterly vulnerable from how exposed and unworthy you are standing before it. Yet, ready or not, here the horizons comes towards you ("coming forth")...
Line 2 - It is now sensed that it is a woman that is being spoken of. The beauty that you have tried to understand it now shown to be a valley between her breasts ("mountains"). It is important that it is not that which we sexualize (the breasts themselves) that are beautiful and remarkable; or not them alone, anyway. But this is perhaps still too literal. What does this mean, that the valley is more beautiful than the mountains? Perhaps that the bare middle of the chest, in its innocence, in its non-sensationalistic and non-overly-sexualized element, represents what is truly the center of the sexual act, the beautiful part, and what makes it truly enjoyable? Perhaps then it is not merely those things with which we sell porn using, and tell vulgar jokes about, that we should glorify, but the whole person? We are sexual beings, not sexual parts.
Line 3 - [I'll tread lightly here...] Verdure ("Verdant") has very specific connotations for me, used as it is in Orthodox prayers about heaven and the afterlife, "where there is no sickness, sighing, etc." It is a word I now completely associate with life and joy and beauty. And if you take the word in that way, and think about the female body, below the breasts, when speaking of sexuality, well that's obviously [the female
lovely bits]. The azure above is perhaps a bit more difficult for my fictional (but completely sincere) interpretation, but off the top of my head I would say a pretty face, a royal face (regal colors), something that reminds you of a beautiful blue sky.
Line 4 - This could have several meanings, or rather does have several and many more I haven't thought of. (not that I have any clue what the original author truly
meant) First, the beauty and awesome nature of it is enough to make you die, not literally, but in the same way that we speak of "spiritual deaths," that is to say, in a symbolic way. People are said to die from loneliness or heartbreak, but here the person dies a symbolic death from an overabundance of joy or love or beauty. He romanticizes (perhaps fairly, perhaps not) the past, when things were not so sexualized, when images and talk of sexuality had not yet permeated our culture, when there was a sense of the sacred, not simply of religious and divine things, but sacred in the sense that some things were better experienced than discussed in the open for all to hear. Perhaps he (I assume it is a he) thinks that this thing he is experiencing is what it might have been like in ancient times, before porn and dirty magazines and racy books and such began to prosper. We know that the ancients could be just as interested in that stuff, e.g. there was sexual graffiti and images on the walls of Pompeii, but would such over-sexualization have existed in most Christian cultures? Probably not. So like a spiritual warrior, defending the sacred and abiding by it, this fellow is getting to experience that which gives him an abundance of true contentment and pleasure, and maybe a glimmer of that beauty and awe that he had long hoped to experience and understand. That it took the form of a woman, with a discussion of sexuality--well why should that strike us as a strange thing? What is more beautiful or lovely?
(This turned out to be longer than I thought. And I was able to keep it cleaner than I thought I would be able to
EDIT--I hope I haven't done any harm here. I mean the above seriously, with sincerity, even if it shows me to be a bit odd. As I said, I do not know what the intended meaning was, though I'm pretty sure it wasn't close to my interpretation
I suppose many (most? all?) interpretations say more about the interpreters than they do the original material...