An interesting thing about sheep - they are born with a nature that makes them want to be free spirits, insistent on doing what they want to do.
When Katie and I were in Israel, we saw a shepherd walking with a sheep he was carrying on his back (tenderly circled around his neck). Our guide explained that this was common, not because the sheep was sick but because the shepherd had broken the sheep's legs.
It sounded cruel, of course, but he explained further.
Apparently sheep do what they want to do no matter what the shepherd asks of them. The problem is that they will nibble some grass that seems appealing, and then nibble some more after that, and then nibble some more after that. Eventually they will wander off because of this progressive appetite and be somewhere far away from the shepherd. And since they are not near him, they are prone to attack from wolves that the shepherd would normally fend off and protect the sheep from.
So the shepherd will break a sheep's legs and carry the sheep on his shoulders. Not because he is cruel, but because he is loving. In this way he also trains the sheep to know his smell, and thereafter to stay by his side and take genuine security in his presence and protection.
Because of this image - of sheep following a shepherd - they sometimes are used to describe something negative. Ironically, it's quite the opposite - by following the shepherd, they actually take part in life versus a death that is created by their own appetite.
Maybe that's why Jesus came, and maybe that's why Palm Sunday is something quite powerful for people who have been waiting for their Shepherd to appear. Are you one of them?
"When Jesus landed and saw a large crowd, he had compassion on them, because they were like sheep without a shepherd. So he began teaching them many things." (Mark 6:34)