Reduction in levels of sensitivity is the primary protection against personal pain, suffering and humiliation. In addition to protection from external threats it can also be extended by people to protect themselves from inner experiences and impulses, including sexual feelings, joy, sadness, anger, pain and neediness. Skill in insensitivity towards personal pain can be extended to include the pain of others. This permits a further destructive development into active infliction of pain on others, whether by word or deed, omission or commission. The borderline between passive numbing and active cruelty is poorly defined and easily crossed.