This is just a stub; I will fill this essay in when I have clarified my thoughts on this topic.
The term love is used to mean many things, and views on it will tend to be very personal! I will not attempt to address them all this essay; I will also try to avoid addressing as love things that are commonly mistaken for love, such as desire.
I see two branches of the path toward describing love:
The psychology of love, including cathexis, is discussed very well in The Road Less Travelled by M. Scott Peck; I will re-read that before writing more here!
The classic spiritual description of love is surely 1 Corinthians 13, and I will use that as my starting-point.
Also important is that it is not that we first loved Him, but that He first loved us [cite].
Surely the most important thing about love is that it is a characteristic of God, and the next most important is that it is an ability that he has given us, presumably as a part of our being made in his image; and in this I have great joy.
Whether seen psychologically or spiritually, it is natural that love transforms relationships (and relationship) and so transitively transforms society -- by leading to true forgiveness of trespasses (which is not the same as an infatuated refusal to see anything wrong in an object of desire (whether or not that object is a person when seen by other than the infatuee!)
So what then is love as a whole?