I don't think that humans collectively will turn up any new emotions, but to individuals, I think there are always new ones to be discovered. Even in my 30s, I have times when I feel a way that I've never felt before about this or that, both for negative and positive feelings. Obviously, we can't really impart our feelings to others, so although I know others have felt as I feel before, it's impossible to get the gist of a feeling through another's description. A feeling is purely qualitative; that is why we respect writers so much who have the ability to convey feeling through words, I suspect, because it's as if they've put themselves in our shoes and are able to tell the world exactly how we feel....do we know every possible emotion and it's a matter of the combination, intensity, and cause of the emotion?