[T]here are aphorisms that, like airplanes, stay up only while they are in motion.

Nabokov’s comparison suggests that certain aphorisms—compact, seemingly self-sufficient truths—depend on momentum: they persuade only while the reader’s attention is carried forward by wit, rhythm, or rhetorical force. Like an airplane that requires continuous motion to generate lift, these sayings may not withstand being stopped, scrutinized, or applied too literally; their “truth” is aerodynamic rather than structural. The image also hints at Nabokov’s skepticism toward ready-made wisdom and his preference for precision over moralizing generalities. An aphorism can feel profound in flight, but once it lands—once you test it against experience or logic—it may lose altitude and collapse into banality or contradiction.