The opening lines—"Just Caesar, just Napoleon, only Garbo, so just Petrov is enough... You don’t want to dance with the great Petrov? Don’t be a silly horse"—immediately set the tone for what follows. How could “Linda” (Ginger Rogers) possibly refuse to dance with this remarkably humble and unassuming man (Fred Astaire) when they begin their journey on an ocean liner headed toward New York? As the voyage continues, d…