Exactly how the marketing funnel works The earliest version of a sales channel that I have the ability to find is this from 1904 by Frank Hutchinson Dukesmith, editor of the Salesmanship magazine Here, Dukesmith introduced the concept of four stages that cause a sale: Interest, Passion, Need as well as Conviction. Almost half a century later, an advertising and sales exec in the pharmaceutical market, Arthur F Peterson, published the adhering to image in his publication, Pharmaceutical Marketing, Detailing, and also Sales Educating: