When a person is referred to as a "sheep", it means that s/he mindlessly follows the crowd/majority without using his own brain, rationale and sanity (Quora).Sheep's choose to follow and can be led astray if they don't have the right guidance. But we are not talking about someone being led or wanting to follow the crowd in this book. This book is about the mental silent killer of ones hopes and dreams. At some point in your life you have allowed this dark cloud to hover over you because of other people's negative thought and projections about you it has overtaken you. The black sheep is an identity given to a single person in a family job, school, community, culture etc. Someone that don't quiet meet the standards in which a group of people perceive they should. To be referred to as a black sheep is to describe someone who feels left out. Basically, the outcast of the family or group because they choose to do other things than live up to their parents' or peer's standards (UD).