Here's what I wrote in 1999 about John Caples and what was arguably the greatest mail order ad of all time:
It's hard to imagine that John Caples was virtually a virgin copywriter at Ruthrauff & Ryan in 1925 when he penned this masterpiece. To fully appreciate his contribution, consider the state of the art at the time.
The roaring 20s were a time when many mail order copywriters were still influenced by rock 'em, sock 'em medical potion peddlers. At the other end of the spectrum were advertising stylists like Raymond Rubicam, Theodore MacManus and Jack Rosebrook.
John Caples came along and created a hybrid genre, fusing style with salesmanship. "They laughed when I sat down..." even by today's standards is a rarity: a mail order ad backed by a big idea. See gang, it really can be done. And Caples was doing it way back when your grandfather was out trying to score some bootleg booze.
This engineer-turned-copywriter eschewed the opinions of his persuasive but misguided contemporaries. He demanded facts. Caples was an early advocate of source codes to track advertising results. He pioneered the use of split-run tests of different ads to sell the same product in the same publication at the same time. And he proved that in many cases, the more you tell, the more you sell.
John Caples generously shared what he learned in some of the most important advertising books ever written. In fact, in the foreword to the seminal Tested Advertising Methods, Caples disciple David Ogilvy called this copywriter "one of the most effective there has ever been."
In 1973, John Caples was inducted into the Copywriters' Hall of Fame and assumed his rightful place next to the other giants of advertising. All direct marketers owe much to this humble man who gave us so much.