They couldn't send for a printed copy of Jesus' latest message. Jesus was an effective communicator. He knew instinctively what most of us need to learn - people remember stories and illustrations best. Images give us a handle on truth. However, there are limits in using images and illustrations.
Most illustrations have one central truth.
As we think about a few images and illustrations of sanctification, keep this in mind. Be careful not to go off the deep end, taking these illustrations as allegories and forcing every aspect to mean something. If taken too far, all illustrations eventually break down. If we stick to the central point of the illustration, these will be extremely helpful in understanding aspects of God's sanctifying work. The ancients were familiar with rituals of sacrifice.