The Lord God is critical of what seems to come naturally to sheep - pushing with flank and shoulder and butting each other with horns. Maybe the same is true for us for when push comes to shove we would prefer not to be on the receiving end. But God as shepherd prefers lean sheep to fat ones and promises to bring back the stray, bind up the injured and strengthen the weak. The image of God as our shepherd is for the encouragement of all who have been pushed and shoved by events beyond their control so that rescued from the clouds and thick darkness of despair they would be well watered and fed on the good pasture of hope and no longer be ravaged by doubt and fear. And if we feel secure we might be less likely to push and shove and scatter others to preserve a place for ourselves which would be pleasing to shepherd and sheep alike.