Love... We think about it, sing about it, dream about it, lose sleep worrying about it. When we don't have it, we search for it; when we discover it, we don't know what to do with it; when we have it, we fear losing it. It is the constant source of pleasure and pain. But we can't predict which it will be from one moment to the next. It is a short word, easy to spell, difficult to define, impossible to live without.