I'm not feeling sad, but the gamut of emotions - particularly those relating to love (gained and lost) are occupying my thoughts at the moment. Luhmann says "love isn't a feeling; it's a pattern of communication" (or something like that). I think that's quite a revolutionary statement, and deserves some serious attention. But the love of lovers is not the same as the love of one's children, or friends, or the love of music, or knowledge. Luhmann's description may fit, but it needs thinking about.