R’ חיים הלברשטאם, the גאון of Sanz, related that he received an inquiry from a רב who didn’t know a straightforward רש״י. “When I wrote my response to him,” רבי חיים said, “I didn’t know by which title to address him. I couldn’t call him גאון because that would be a lie. But not calling him גאון was also difficult because that is the honorific he is accustomed to. So I decided to call him גאון because in the days of the גאונים, they also didn’t know פירוש רשי.”
06/10/2021