Nostalgia is a file that removes the rough edges from the good old days.

Larson treats nostalgia as an active tool rather than a passive feeling. A “file” removes burrs and sharpness; likewise, nostalgic memory abrades away the painful, boring, or complicated parts of earlier times, leaving a smoother, more attractive surface. The joke carries a warning: when we praise “the good old days,” we may be responding less to history than to a curated recollection shaped by longing, selective attention, and the mind’s tendency to soften trauma over time. The metaphor also implies distortion through repetition—each pass of the file changes the object—suggesting that the more we revisit the past sentimentally, the more we reshape it.