Nostalgia is a powerful feeling of both pleasure and sadness when looking back on happy memories; the sadness comes from the knowledge that such times are past and will not come again.

Nostalgia can be triggered by a sense experience in the present—a sight, a sound, a smell. For example, after a long absence, you might be driving through your hometown, and the sudden sight of a familiar building could trigger a nostalgic feeling about that time in your life, along with a flood of old memories. Hearing a song from the past can also evoke a powerful feeling of nostalgia. It can suddenly bring back the whole flavor of the time when you first heard it and used to listen to it a lot—you might find yourself remembering exactly what you were doing in those days, what your situation in life was, what you thought and felt in those long-gone days. Nostalgia can be triggered by a smell of something that takes you back to a former time when you last smelled it—the scent of a flower, for example, or the smell of a certain food as it is being cooked.

In “The Tropics in New York,” the sense of sight prompts nostalgia.