Jesus often used word pictures to teach eternal truths.  These word pictures, called parables, have the remarkable quality of engaging the imagination of ancient and modern readers in order to teach spiritual truths.  In Mark 4 Jesus uses several images to describe what His kingdom is like - seeds, soils types, and small oil lamps.  These parables show us that the kingdom of God is not "other worldly”, but right in our midst as the Holy Spirit dwells with Gods people in ordinary life.