hmmm... always evolving, so cannot be defined. Sounds about right. Or maybe it is like the discovery of something. At first you think you can define it, describe it, to the last detail, then as you discover more, you throw your first thoughts out and feel maybe foolish for thinking you knew so much... then as you go further, you may be start to see that some of what you initially thought could be true, but it is more than that... and it is eternal, so you never stop discovering it. Sometimes it may seem to change or evolve, but maybe it is just our perception of it that changes. But isn't that what makes it so wonderful? ... and no matter what we do to it, or think about it, it's still there. Even when we turn our back on it.. there it is, still there waiting for us to turn around and face it once again, till we fully embrace it.
Just a thought.
(a side note: I was imagining describing and discovering God, to come up with that^ description/idea. I figure since God is as pure a love as you can find, that to describe true love, you'd have to look to God to really understand it)