In Sefer Yehoshua, Yehoshua takes over Moshe’s role of leadership of the Jewish people. Throughout our history, every Jewish leader has had a central characteristic which defined them – Avraham was defined by the middah of chesed- kindness, Yitzchak represented the middah of gevurah- strength and Moshe, anavah – humility, etc… What was the central characteristic that defined Yehoshua?
The Midrash says that the reason why Yehoshua was chosen to lead the Jewish people after Moshe was because he used to set up the benches in the Beis Hamedrash for Moshe to come in and teach Torah. Why should it be that because of this he became the next leader?
The Gemara says that Moshe is compared to the sun and Yehoshua to the moon (Bava Basra 75a). The job of the moon is to reflect the light of the sun at a time when the direct light from the sun is not able to be seen on Earth, i.e. at night. Similarly, Yehoshua’s defining feature was that he continued on from where Moshe left off, living his legacy, doing what Moshe would have done if he were still alive. Thus, Yehoshua is described in the Torah as ‘the helper of Moshe’ (Shemos 24:13, Bamidbar 11:28) – a phrase which appears in the opening pasuk of Sefer Yehoshua too. With this in mind, it is not surprising that we find many similarities between Moshe and Yeshoshua. Both are described as an ‘eved Hashem – servant of Hashem’ when they die, and both, as the Rambam and the Netziv state, had the halachic status of a king. The events that took place in Yehoshua’s reign shadow many of the events from Moshe’s time; Moshe split the Red Sea and Yehoshua split the Jordan River; Moshe oversaw the first Korban Pesach in Egypt as well as the sole Korban Pesach offered in the desert, and Yehoshua oversees the next Korban Pesach in Gilgal. Note how the pesukim reflect this idea, describing the way that Yehoshua offered the Korban Pesach “like Moshe” (8:30-35). In addition, they both married converts (Tzipporah and Rachav). Moreover, even that which they bequeathed to us highlights this idea – Moshe gave us the Torah, and Yehoshua gave us Eretz Yisrael. The job of the Land of Israel is to reflect the Torah. Finally, the Gemora says (Yevamos 96b) that Yehoshua did not need to preface the Torah he taught by saying ‘this is the way Moshe explained it to me,’ since everyone knew that all of his teachings came from Moshe.
It was for this reason that Yehoshua was chosen to succeed Moshe and bring the people into the Land of Israel. The Maharal explains that Yetzias Mitzrayim and entering Eretz Yisrael was initially supposed to be one process – just as Moshe took us out of Egypt, he would bring us into Eretz Yisrael. However, after the sin of the spies and Moshe hitting the rock, Moshe was prevented to enter the land. The B’nei Yisrael were then given the person most similar to Moshe to complete the process in his stead – Yeshoshua.
Based on the above approach, we can suggest that when Yehoshua set up the chairs in the Beis Hamedrash, he demonstrated that he was the one who facilitated Moshe’s teaching; he showed that, to some extent, he was a partner of Moshe. Thus, he merited to continue as leader of the Jewish people after Moshe. He was the moon that shone after the sun of Moshe had set.