Happiness, they say, is a state of mind.   It is not what you have and it is not what you do.  It is how you feel as you are going through the motion of living.  But then, it is not like emotions either, that change when the sun shines or the rain pours, or even for absolutely no reason at all.  Rather it is a constant (like a background noise that ceases to have no sound because one ceases to listen to it) whose presence is noticeable only during its absence.  Indeed, it is often in moments of unhappiness do we realize how happy our lives have been!  In times of loss do we appreciate how much we actually own.