Eventually - Why Not Now?" - Gold Medal Flour (Saturday Evening Post, May 25 1918)
The pattern
This still is filed under Campaign line as series.
Define
One line that can be replayed across executions so the campaign is a family, not a one-off.
Mechanism
Repeatable frame. Each ad is a verse. The line is the chorus. Recognition compounds because the structure is stable.
Verdict
We will run more than one execution and need them to add up in memory.
Why it works
The headline is one word that cannot stand alone, so it forces the reader into the first body line to complete the sentence - the copy literally begins with a dash. That mechanic drags a slogan-only page into being read. The slogan itself carries an implied rebuke, you will come to this anyway, which converts a brand line into a nudge toward immediate action, and the repeated reversed band at the foot drills it a further three times without spending headline space. The brand then deliberately shrinks its own share of the sale by telling you to use less wheat flour, which buys credibility for the one place it does ask to be chosen.
Steal this when
You need an institutional or public-interest message to sell product without looking opportunistic: lead with the shared obligation, recommend the reader use less of your category, then position your brand as the specific right choice for the part they cannot avoid.