The Sherwin Cody Course In English Grammar, . . . So Revealing
The "Revealing" part of this story is the world class stunningly simple headline Cody used for his sales copy:
"Do you make these mistakes in English?"
Wrapped up in that headline is all the firepower you will ever ever need when reaching for solid conversion rates. I mean to say that that powerful headline was responsible for incredibly high conversion. And, the product was seemingly nothing special. It was a rather dull and mundane course in English grammar that the recipient had to interact with like homework to receive its value. Yet, the headline powerfully converted time and time again and the courses provided good value to the recipients. This was proven.
The "Revealing" nature of such a powerful headline is that it can be adapted to virtually any product or service you are promoting. It's the kind of firepower you need when ever you are seeking a "breakthrough". The adaptability and sheer draw of the main tenant: do you make a mistake; offers an irresistible suggestion to the reader that literally pulls him into your copy.
None are more hopelessly enslaved than those who falsely believe they are free.
--Johann Wolfgang von Goethe, Elective Affinities (1809)