@Rob-hin: Love, like any human behaviour which has both an overt behavioural part (we act in a certain way with certain functions) and an intrapsychic, experience part (in our private minds, we experience certain feelings), is
both a chemical and a "spiritual" thing. Unless you believe in mysticism and transcendence,
the brain and the mind is one.
Every thought you think, every emotion you feel, every act you do, will elicit a lot of chemical events in your body. Many chemical events in your body, will elicit phenomena you can experience. Our bodies are the fields where our genetic disposition and environmental factors interact throughout all our lives.
Love can be described from a functional evolutionary perspective. Every species must reproduce in order to survive, and for humans, reproduction include long term rearing of offspring since humans are born with earth's most undeveloped brain and most dependent offspring. Humans are a group living species, so we need to bond, to form
attachment to each other in order to survive. What psychologists and evolutionary antropologists call attachment, is what many people call love.
Apart from this, love can also be described as an intrapsychological experience, an emotion. Emotions are drives that makes us behave in certain ways. A behaviour must be
rewarding, otherwise the organism will not do it. Thus, eating, having sex or loving is rewarding, ie it feels pleasurable.
Love, as any other behaviour, can also be described in a biochemical way. There is however not one single emotion or one single behaviour, we know so much about so we can describe the entire process. We can however describe parts of some emotions, for instance it is known that the hormone oxytocin and the monoamines dopamin and norephinedrine are involved in the chemical events that are in action when we love.
So what is love? It is a functional behaviour which developed during evolution. It elicit certain behaviours, emotions and internal experiences that in turn are more specifically formed by sociocultural norms. These behaviours and internal experiences are mediated by biochemical events that are only partly known. However, at a phenomenological level, the effect is well known