A thought that has struck me as odd concerning "enlightnement" is that the popular view, and from what I can tell, the view among some Buddhist traditions, is that once you have it, you have it. How can this make sense in an ideology that above all else, stresses the impermanence of everything?
I find myself practicing, and I guess following, the Soto lineage of zen which seems to place the least emphasis on the concept of enlightenment. I think the Soto way is the most fundamental bare-bones form of Buddhism in the way that handles concepts like this. In barely feeling comfortable in going over this, keep in mind, this is just how I understand these things right now, and don't consider myself in anyway authoritative.
The main expression of practice is zazen, which is seated meditation. You sit there facing a wall trying not to think. There's no real goal or focus, you just try to keep your mind from latching on to the thoughts that pop up. From all its being called a "natural state," it sure doesn't seem so. The purpose is to stay in the moment and not let our minds wander to thoughts of the past or future. I guess as advanced social creatures, our minds try to use the downtime to build a structure of reality around the present to give us a sense of security.
This sense of security is false, though. We can't revisit the past, and just as our prejudices cloud our view of the present, they further cloud our views of the past every time we recall them. Thoughts of the future are even more dubious because we haven't even seen what will happen. So seeing through this illusion could be called enlightenment, but you have to actually experience it, understanding it as a concept is not enough anymore than understanding that sugar is sweet lets you taste it in its absence.
Letting go of that security is usually referred to as an aspect of Buddhism's "unattachment." The present happens on its own and will never happen like the past again. (Like the metaphor of never being able to put your foot in the same river twice.) So, if practiced honestly, zazen can be seen as enlightenment itself even if thoughts pop up, because you are expressing the impermanence of the moment by letting thoughts go.
Now sitting is not the only time we're supposed to practice this, but it is good exercise in that we minimize distraction to build up our ability to make it easier to find that state when we're most in need like stressful situations.
How can I relate this to food? Well take the metaphor of the perfect meal. Think of the best meal you've ever had. Not just the taste of the food, but everything: the atmosphere, the people (or lack thereof) you enjoyed it with... Did it eclipse all the stress of your day so far, or compliment how wonderful it was going?
Now consider this: it will never happen again. No matter how hard you try, you can't orchestrate all those circumstances again, and even if you could, you would still be hampered by your expectations of how awesome it was the first time.
If we back up a bit, and limit the example to just the food, there's a reason we use the word "best." By definition, it can't be equaled, and to top it would rob it of that quality.
Your favorite food wouldn't stay that way if you ate it all the time, either. So, if enlightenment is the perfect meal, each meal is a moment in time, and we of course want each meal to be the best ever, we can't compare one meal to another. If breakfast was too awesome for words, and lunch doesn't live up to it in comparison, not only will the experience of lunch be tainted, but we'll lose some of the sparkle from breakfast. We might as well not even eat lunch if we're hoping dinner will be better or even compare to breakfast. What happens if breakfast the next day is awful? What will we expect lunch to be like? In the restaurant industry it's said that you're only remembered by someone for the last meal you served them.
Is this making sense? Just as we consume meals, we consume moments. Some moments leave us feeling empty and unsatisfied. Some over stuff us with pleasure until we want to burst. Comparing the present to the past or the future doesn't make sense since we can't re-eat a meal once it's complete or before its prepared. Our only hope of happiness is to consume the present moment without comparison and enjoy it for what it is. That right there is what I've come to understand is enlightenment.
And as far as enlightenment being permanent. We can't eat the same meal forever. Some meals may inspire similar feelings as others, but each time it will still be a different meal. Does this cheapen the meaning of enlightenment? I don't think so. I think it makes it more precious and not so exotic as to seem unattainable.