A Light Unto the Nations

Sometimes people are under the impression that the concept of being a 'light unto the nations' is an invention of the moderns as opposed to an underlying facet of Judaism. To counter this point, I suggest people look at the Aznaim L'Torah (R' Zalman Sorotzkin) to Deuteronomy 9:24; divrei hamaschil מַמְרִים הֱיִיתֶם, עִם-יְהוָה, מִיּוֹם, דַּעְתִּי אֶתְכֶם.