If you walk down the street and smile at someone, that will get passed on to the next person. That has the power to change someone’s day.

Margulies frames kindness as a low-cost, high-impact social act. A simple smile is presented not merely as personal expression but as a contagious signal that can ripple outward—one person’s improved mood influencing how they treat the next. The quote draws on the idea of emotional contagion: small gestures can shift the tone of everyday interactions and, cumulatively, the atmosphere of a community. Its significance lies in emphasizing agency in ordinary moments—suggesting that changing someone’s day (and potentially their behavior) doesn’t require grand interventions, only mindful, humane attention to others in passing.