"The Lord promises to play the part of a shepherd to each of His sheep. In Palestine the shepherds care for their sheep, putting them in the folds in the evenings and allowing them to spend the nights there. In the mornings the shepherds lead them forth to green pastures and then to still waters, where they may lie under the shade of the trees during the heat of the day. They lead them from one place of rich pasturage to another and finally guide them back through the dark valleys to the fold for the night. It is the shepherd's responsibility to make all provisions for the sheep and to protect them. Thinking in terms of the shepherd's care of the sheep, then, David was led by the Spirit to express, in terms of the shepherd's caring for his flock, God's provision for and care over all who accept Him. The Good Shepherd leads them through every difficulty and protects them as they pass along the journey of life and will lead them into the fold of eternal rest and security throughout the ages of the future."

http://www.ariel.org/dlc/dlc-sma-35.htm