When in 1800 Parson Weems published “A History of the Life and Death, Virtues and Exploits of General George Washington,” this and later editions would become the source of treasured chestnuts such as the tale of the 6-year old George killing his father’s cherry tree or the older Gen. Washington kneeling in the snow to pray at Valley Forge.

With its saccharine moralizing and portrait of larger-than-life integrity, it isn’t unlike today’s tales about former Federal Bureau of Investigation director James Comey. Except that the...