The Torah’s account of how God goes to such lengths to persuade Moses to accept the mission of leading the Exodus demonstrates that no one could substitute for Moses, because no one else in that generation was so well suited to become a national leader. The reason is not only Moses’ rare personal qualities (he is uncommonly righteous, humble, and actively committed), but also because only Moses had received the training that that mission required.
Moses combined three lines of self-identification: Jewish, Egyptian and Midianite. No other Jew of his generation had Moses’ broad outlook. A leader must see the world through the eyes of a free man. He must be a man of the world, and not a man of any one particular place.
Aaron is not in a position to lead the Exodus. He is accustomed to living with the Jews in slavery and supporting them in difficult times, but he has no understanding of how Egypt functions as a state, nor (what is all the more important for a leader) how the peoples of the world relate to one another, and how human development progresses.
Moses, raised as a free man in Pharaoh’s home, incorporates both Jewish and Egyptian perspectives. Through his years spent in Midian, observing the conflicts of states and of peoples from the sidelines, he acquired a new, universal outlook on the world. No other Jew of that era had that knowledge or understanding.
The leader who was to bring the Jews out of Egypt could not be just a slice of the people – he had to remain somewhat distant from them, in order to see into the future. Of all the Jews of that time, Moses was unique in having spent most of his life in the wider (i.e., non-Jewish) world, which afforded him a global perspective. Because the Exodus from Egypt is a world-class event, its leader must, on the one hand, be himself a representative element of the people, but on the other hand, be able to understand how a state operates and how it is governed. And finally, he must have a panhumanistic, universal perspective on the meaning of current events.
In other words, a Jewish leader must be a person who lives in all possible worlds at once. Moses was just such a person, which is why only he, and no one else, could lead the Jews out of Egypt.
This also means that the wheels of the Exodus were set in motion from the moment that Providence sent Moses to be reared and educated in Pharaoh’s palace, in preparation for his future role as the leader of a nation. Although every Jew considered Pharaoh’s order to throw newborn infants into the Nile a senseless, monstrous atrocity, that decree was in reality a necessary precursor to the Exodus (but this, needless to say, in no way negates or condones Pharaoh’s criminal actions).
We find a modern analogy to this idea – the establishment of the necessary conditions for the creation of a leader – in the historical need for the assimilated Jew, Theodor Herzl, to arrive on the international Jewish scene. Herzl became the founder of the political Zionist movement that ultimately led to the creation of the State of Israel – the “Exodus” of our era. Even before Herzl there were rabbis who spoke of the need to resettle the Land of Israel and to create a Jewish state, but none of them envisioned accomplishing it through international conferences, media coverage, negotiations with world powers, and so on. Activities of this kind were extraordinary and incomprehensible to them. Traditional Jews were therefore, in principle, incapable of creating an effective Zionist movement.
We also note that according to the approach of the Gaon of Vilna, on whose writings the concept of religious Zionism is based, the era of Mashiach ben Yosef, “Messiah son of Joseph” – the era of the creation of the first stage of the Jewish state in the Land of Israel – began in the late eighteenth century. The Gaon of Vilna considered the French Revolution just such a “launch” of the Mashiach ben Yosef “platform,” because it brought the Jews out of isolation and made them full citizens of modern states, on the basis of which Zionism could gradually emerge, albeit only a full century later.