All markets go through three stages.
Knowing what stage your market is at helps you determine what you must focus on in your letter. Under those circumstances you have to explain what you are selling in such detail and make it so appealing that somebody who has never seen or experienced what you are talking about will not only understand what it is, but want it. Imagine, for instance, being the first person to offer a credit or charge card. I am choosing that example because the business is one I know very well that has gone through all 3 market stages in the last 40 years. When the first charge card, Diners, came out, a friend tried to explain it to me.