In discerning what is true from what is false it is best to focus more attention on what is genuine than what is counterfeit. It would be tempting to train people to identify what is fraudulent by focusing a great amount of time on what is false. However, because falsehood is always changing, it is more beneficial to focus on what is unchanging. Knowing and identifying what is false can be done best by knowing and understanding what is true. A person who studies and understands what is true is necessarily equipping himself to discern what is false.  - Tim Challies, The Discipline of Spiritual Discernment, p. 142.