The textbook traces the evolution of the advertising agency model:

• Pre-1880: Advertising agents were simply middlemen who bought space from newspapers and resold it to advertisers at a profit
• ~1880: N. W. Ayer and Son of Philadelphia introduced the “open contract” — they would be the advertiser's sole agent and price ad space at cost plus a fixed commission. This eliminated price competition among agencies
• By 1892: Ayer hired the first full-time copywriter; other agencies followed
• 1893: The American Newspaper Publishers Association agreed not to offer discounts to direct advertisers, forcing all advertisers to use agents
• 1901: Curtis Publishing Company (Ladies' Home Journal) adopted the same practice; magazines followed
• 1919: The cost-plus-commission basis was accepted industry-wide, with the commission standardised at 15 percent — a rate that remained the industry standard for decades

This transformation turned advertising agencies into creative service providers (writing copy, creating logos and slogans, managing artwork) rather than mere space brokers.