Why do some phases of sin and disease often seem more tenacious and difficult to overcome than others? Is evil really able to inject more power and tenacity into cancer than into colic? That is its claim, but its claim has no law of Truth to support it. In a paragraph in the Christian Science textbook, "Science and Health with Key to the Scriptures," under the marginal heading "Diseases not to be classified," Mary Baker Eddy says ( p.