The Good Shepherd lays down his life for the sheep. The society of Jesus' day largely centered around farming and livestock, things that are not always so familiar to those of us who live in today's age of industry and information. Take the verse quoted above for example. Well, perhaps it would be a good idea to talk a little about sheep and shepherding to help see what Jesus meant.
Sheep are animals that are raised for food and for the wool that they produce.
Raising sheep was very important in Biblical times so it's not surprising to find that the Bible mentions them over 700 times. While sheep tend to be somewhat curious about their enviroment, they also tend to be not very smart. Unfortunately for them, this combination of curiosity along with a lack of intelligence often leads to problems. For example, it's not unusual for a wayward sheep to find itself caught in a thorn bush, or stuck in a crevice, or falling off some hillside cliff. If that wasn't enough, sheep are unable to locate food and water on their own like other grazing animals.