Why White Matters

The wish to see Jews in white on Shabbos rests on what white stands for: purity and happiness. As long as people are gloomy and dark, dressed in black and drab colors, Moshiach will not come on his white donkey. If wearing white is so important, the lesson asks, why not at least try? Satan's threat to make everyone into "chasidim" meant chassidim who would be his own, people who wear white outwardly but are black inside. Reb Yitzchak was not frightened by this threat.