Sheep are a good metaphor for people. They like to be with others, willing to follow a dominant leader but also like to make sure they can get away on their own. They are easily frightened and hate going through narrow gaps. They like going up but are frightened to go down. Therefore, when they are out on the hillside, they can easily wander off, clamber up a steep bank, and not be able to get down again. At that point, they are lost; away from the safety of the shepherd they are vulnerable to predators, and unable to take any initiative to help themselves.