Our body is consist of skin, muscle, bone and etc. Among them, bone is based and center of our body. Teeth are also bone. And tooth is a only one organ of bone which can see out side without knife. Ego is also center of our inner side like bone. I express rotten ego metaphorically by using cavity. Cavity means rotten bone and rotten ego. They have a common which is located in center. Body and spirit are both mine. So I treat them similary. When someone’s ego is not healthy, he/she can easy to fall bad temptation and ruin himself/herself . They ruin themselves . In my view they look weird like this picture.