If emotions are guesses and predictions, then joy is the prediction that there will be good things, better things, transformation.
It's not everything is going to be okay, but it is everything will be good enough, better, worth being grateful for.
It's all that we see in our lives and in the world that convinces us that we can always find a path to peace, equanimity, love.
If I apply it within the four qualities, it goes like this. The wish that everyone be happy and free, awakens the hope, possibility and prediction that this will be so. What makes this feeling habitual is the equanimity that supports it, nurtures it and increases the circumstances and possibilities for joy.
