I read somewhere, can't remember the writer, that grief is the most perfect form of desire. Pure desire exists independently of its object, and when we desire something that no longer exists we are privileged to experience the purity of desire.
When my son was two years old or so I found him weeping in the kitchen. He wanted something to eat. This was no big deal - he was a chubby and well-fed little fellow, but what he had just discovered wasn't hunger, it was desire. To desire something we have to know we don't have it.
This leads to the interesting conjecture that desire exists independently of the thing we think we desire. Maybe that's why, once we get what we desire, we are often filled with anit-climax, with a sense of greyness. We have confused desire with desire FOR something, and have misled ourselves.
KInd of like walking. As we walk along we don't watch the pavment in from of our feet - we focus our gaze on something in the distance. It's not our goal, it's just a way to focus ourselves as we walk. I have heard it said that when a dancer does a spin, they need to focus their eyes on a specific object afterwards, to regain their balance and perspective. Focussing our gaze on a somewhat distant object gives us balance and direction, and has nothing to do with the thing we're looking at, really.
Could desire have the same function? We operate always by desire. If we desired nothing we would probably settle down in a chair or a couch and never move again. The trick is to remember to look THROUGH the thing we're desiring, remembering that when we get to it, desire won't be leaving us, it will just shift its focus.
In the Tarot, this is the meaning of the Five of Cups. It warns of what can happen when we associate desire with something we think we can have. Love and desire are a fluid medium, expressed by cups. When we try and enmesh them with a physical thing their flow is stopped. It is like damming a river.
At its most pure desire is like music. There are times when your soul is simply impaled by music, when you think you may die of it. You let it go through, and maybe you dance. I wonder sometimes if music could kill by its beauty. Only if we let it get stuck, don't let it through, try and hold it somehow. Desire can lead us deeper into the dance, and if we don't block it by trying to hold the thing we think we desire, we dance right through it. If we don't, we can get chunked up by the Five of Cups.