It is often depicted in stained glass windows. Having grown up in the city, I had little experience of sheep or shepherding. I have always had the idea that this idea of the Good Shepherd was vaguely insulting. If the Lord is my shepherd, then that means that I'm a sheep. And I don't really want to think of myself that way.
Sheep are docile and passive creatures.
They don't think for themselves. And surely the church has done significant damage to people by encouraging them to be obedient and submissive. As Walter Wink has noted, the church's teaching has played into the hands of tyrants and totalitarian rulers. So that people have not resisted abusive power. They have been submissive in the face of tyrannous hierarchies in church and state, corporations and schools.