Why do we feel nostalgic?

Human beings have an incredible capacity for memory, and while this can be helpful when remembering where we left our keys, there are some grey areas of memory that are not so easily explained. When you think back with fondness on the past, perhaps in a moment of sorrow or longing, that emotion can be complex and even painful at times. The classic mention of the “good old days” is essentially saying that the past was better than the present.