My father, a Judaic scholar and a stickler for correct Hebrew, always scolded anyone who greeted him with ḥag same’aḥ, “happy holiday”—or as American Jews more commonly spell it, chag sameach—during ḥol ha-mo’ed, the intermediate days of Passover and Sukkot. The right expression, he told the greeter, was mo’adim l’simḥah, “[May] Sacred times [be] for happiness.” Only the first and last days of the holiday, he insisted, were true ḥagim, days whose customs of lighting candles, reciting the Kiddush, and abstaining from travel, work, and commerce resembled the Sabbath’s, and ḥag same’ah should be reserved for them alone.