Scientific Advertising - Claude C. Hopkins
My friend Aleksi put it well when he read this book. He said there are two ways to do advertising.
One, you trust that creativity and artistic hunches will make your advertising campaigns successful. Sometimes you hit a jackpot when your guess is right and your campaign increases your sales.
Two, you create advertising that sells, because you have studied and tested it, to find out what works in advertising, and why.
Claude Hopkins was the first author to do the latter. The book Scientific Advertising is written in 1923 and it was locked in a safe for 20 years because his boss thought the information in it was too valuable to be shared. For example, consider Hopkins' view on testing:
"Suppose a chemist would say in an arbitrary way that this compound was best, or that better. You would little respect his opinion. He makes tests – sometimes hundreds of tests – to actually know which is best. He will never state a supposition before he has proved it. How long before advertisers in general will apply that exactness to advertising?"
Scientific Advertising by Claude Hopkins is packed with metaphors like this. It's entertaining and informative book about advertising that works. Hopkins founded his beliefs in mail-order advertising, and then moved to general advertising because he thought it was easier business to succeed. Most famous products he has helped are Palmolive and Pepsodent.
I wrote a few articles ago that people like Drayton Bird, Rosser Reeves and David Ogilvy swore to Scientific Advertising's wisdom. Ogilvy says "Nobody should be allowed to have anything to do with advertising until they have read this book seven times." – I would make it eight.
Here is a link to buy the book or download it here for free