I think sadness is the feeling which is most experienced by everyone. It seems to be the epitome of all feelings, linking all the known emotions. It is the most raw emotion, because even if you cannot explain why you are sad, you just know it is there. When you're happy you're most likely to have one reason for it. Unlike happiness which is rather sugarcoated and exaggerated when you sense another one's excitement, sadness is bare as the skin-- you could feel it radiate off a person's pores and embed itself onto yours-- and you could understand the pain and hurt. Sadness is beautiful in the purest form; it is good to feel lonely and down once in a while. Because without it, you would never even know what it would be like to experience being happy.