Sadness Understood

For all of my adult life, I have experienced sadness through the mind of clinical depression, a very real, very serious psychological disorder (disease) that manifests itself to the outer world only in behavior. What I had perceived as sadness is not what is commonly perceived as sadness, and I had no idea that this was so, until a recent change in my medication was introduced. This essay attempts to describe what my perception of sadness was, what I assume may be sadness as perceived by others who suffer from this dreadful disease, and what I know it now to be.