In the old generations, the Talmud remembers, a Jew would not wear black shoes (Taanit 22a). Even in later centuries, in the Jewish towns of Poland, a chasid — a truly pious man — would not appear in polished boots or a short European coat, and would never step out without the gartel, the prayer belt worn around the waist.
To break the custom was not a small thing. A man who appeared in the synagogue dressed like the nobility of his host country would lose caste; the community's quiet pressure, direct and indirect, would turn against him.
This is why one of the most familiar of Jewish household sayings is Minhag Yisrael Torah hi — "the custom of Israel is Torah." The custom is not beneath the law; in a long exile, the custom is how the law walks the street.
The sages are realistic about this. They also quote the other proverb: "Custom is the plague of wise men, but the idol of fools." A custom kept without understanding becomes superstition; a custom kept with understanding becomes a fence around the Torah itself.
The lesson is not to worship the boot or the belt, but to recognize that a people keeps itself alive by the small signs it refuses to drop.
(From the 1901 Hebraic Literature anthology, with reference to Taanit 22a.)