Ah, but where is it?
Who can strain the blue from the sky?
I try to grasp the beauty;
it eludes me, leaving only the body in my hands.
Baffled and weary I come back.
How can the body touch the flower which only the spirit may touch?
Reductionism has been with us so long that most people have forgotten that it is an assumption, not a fact. For example, it is commonly assumed that "higher" forms of motivation, such as love, can be explained in terms of "lower" forms, such as physical pleasure, and that these, in turn, can be explained in terms of certain neurochemical events.
If you take this route, though, you have a lot of work ahead of you: You must, for example, explain how love comes out of physical pleasure by inventing theories -- exchange, equity, balance, ego-defense, self-disclosure, etc. -- that treat love as an essentially economic activity. These always leave you with the embarrassing exceptions where love seems to "cost" more physical pleasure than it enjoys!
More importantly, you are left with the eternal problem of explaining how neurochemical events come to be experienced as pleasure, much less love. Why should certain neurochemical events feel so good? And defining all pleasure as approach behavior only begs the question: Now, why should approach feel so good?
Phenomenology brackets or puts aside considerations of what a phenomenon "really" is, so makes no assumption of reductionism, but instead attends to the phenomenon as it presents itself. In studying physical pleasure and love in this way, I've found that not only do they share certain essential qualities, but that love shows them in a "purer" form. In other words, it would be more fruitful to see pleasure as a derived, limited, or special case of love than the reverse.
I need to make two points before I go on: (1) Consciousness always involves a "view" as well as a "viewpoint." As Husserl put it, "consciousness is always consciousness of...." This is called intentionality. (2) Consciousness is a desiring; it is never disinterested. An experience has a meaning to the extent that it has an impact (positive or negative) on the experiencer.
Pain leads to a confrontation of view and viewpoint: It emphasizes the dualism of your "you-ness" over against the world's "other-ness" by threatening that "you-ness." Pain attacks you or invades you, and you desire less consciousness of it, or less presence of self to it. Other irritations -- itching, hunger, thirst, sexual appetite -- although more complex, share a similar essence: You are highly conscious of yourself-in-need.
Physical pleasure, on the other hand, is the diminishing of this self-consciousness, a release from the confrontation. As implied by the two points above, we never completely lose our desire, but when the "distance" and "speed" of the release are great -- as in orgasm -- we come very close! Watch yourself during those moments: Do you look at the walls and think about new wallpaper? Or do you roll up your eyes and become "one with the moment?" The latter, I sincerely hope.
With physical pleasure, you begin to lose your desiring, your perspective, your self.
Now, let's look at love. When we love someone, we find that our own well-being depends on the well-being of our beloved. "Well-being" is a major concept for me, but let's just focus on pleasure for now: If I love you then (among other things) I am pleased by your pleasure. Yet my own pains or needs are not being dealt with. In fact, I may actually undergo further pain or deprivation in order that you may have pleasure!
Without the "release from confrontation" of physical pleasure, I nevertheless experience a pleasure, when gazing deeply into the eyes of my beloved, that takes me "out" of myself.
And that's the point: Whereas physical pleasure requires first a pain or needfulness, an emphasizing of self, as a prerequisite, love does not. Love is simpler or "purer," than physical pleasure. Or, physical pleasure is a limited love: Your genetic inheritance, through your body, sets up a "mimicry" of love by arranging for a heightening of self-consciousness that can be diminished by behaviors that promote survival and reproduction. In other words, in hunger and sexual desire, we "cause" ourselves pain, the relief of which feels so good we seek to renew the circumstances of that relief -- conditioning! But physical pleasure therefore returns us to where we were; it doesn't take us any further. So, although we "love" to eat and "love" to make love, these things don't quite have the depth of love for a beloved.
Love, however, is itself not pure self-transcendence: Love uses the positive importance of the other to "draw" consciousness away from day-to-day self-world dualism. Love is, in that sense, in the same league as the self-transcendence we find in "flow" experiences such as mountain-climbing, and esthetic experiences such as enjoying the Grand Canyon or a hummingbird. In all these examples, self-transcendence remains dependent -- on the lover, the activity, the view -- and so we remain, in part, passive receivers of "awe."
It is clear that we can more actively control (if that's an appropriate word here) transcendence through the direct stilling of desire in meditation. But the time and effort required, not to mention the immateriality of the goal, are not in keeping with modern life. So I suggest that love is a sort of "poor man's meditation:" While few of us are likely to become truly enlightened, most of us can at least taste enlightenment in our love for another.