Advertising isn't a science. It's persuasion. And persuasion is an art.
Source: In Quotable Business, ed. Louis E. Boone, 1992.
-- William Bernbach, (Aug 13 1911-1982), US advertising executive, copywriter; He pioneered the subtle, low-pressure advertising that became a hallmark of the agency which he founded, Doyle Dane Bernbach, Inc.