The train diagram in the back of the little booklet called "The Four Spiritual Laws". The illustration is, you see a train running down the track, there's an engine, there's compartment cars and then there's a caboose. All the power is in the engine. You can't pull the train by the compartment car; you can't pull it by the caboose. Well if you think about the engine being fact and the compartment cars as faith and the caboose as feeling, the way we live our Christian life is we put our faith in the facts and then God produces the feelings.